SGK Vật lý 8

["B\u2202ng 14.1 C\u220fc \u00c6\u03c0i l\u2260\u00d3ng c\u00abn x\u220fc \u00c6\ufb01nh K\u00e4o tr\u02d8c ti\u2019p D\u00d4ng r\ufb02ng r\u2030c \u00c6\u00c8ng L\u02d8c F(N) F1 =... F2 =... Qu\u2211ng \u00c6\u2260\u00cdng \u00c6i \u00c6\u2260\u00d3c s(m) s1 =... s2 =... C\u00b4ng A(J) A1 =... A2 =... C1 H\u2211y so s\u220fnh hai l\u02d8c F1 v\u00b5 F2. C2 H\u2211y so s\u220fnh hai qu\u2211ng \u00c6\u2260\u00cdng \u00c6i \u00c6\u2260\u00d3c s1, s2. C3 H\u2211y so s\u220fnh c\u00b4ng c\u00d2a l\u02d8c F1 (A1 = F1.s1) v\u00b5 c\u00b4ng c\u00d2a l\u02d8c F2 (A2 = F2.s2). C4 D\u02d8a v\u00b5o c\u220fc c\u00a9u tr\u2202 l\u00cdi tr\u2122n, h\u2211y ch\u2030n t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a k\u2019t lu\u00c0n sau : D\u00d4ng r\ufb02ng r\u2030c \u00c6\u00c8ng \u00c6\u2260\u00d3c l\u00d3i hai l\u00abn v\u201c ....(1).... th\u25ca l\u03c0i thi\u00f7t hai l\u00abn v\u201c ....(2).... ngh\u2039a l\u00b5 kh\u00b4ng \u00c6\u2260\u00d3c l\u00d3i g\u25ca v\u201c ....(3).... II - \u00df\ufb01nh lu\u00c0t v\u201c c\u00b4ng K\u2019t lu\u00c0n tr\u2122n kh\u00b4ng nh\u02dcng ch\u00ff \u00c6\u00dbng cho r\ufb02ng r\u2030c \u00c6\u00c8ng m\u00b5 c\ufb02n \u00c6\u00dbng cho m\u2030i m\u220fy c\u00a8 \u00c6\u00a8n gi\u2202n kh\u220fc. Do \u00c6\u201e, ta c\u201e k\u2019t lu\u00c0n t\u00cang qu\u220ft sau \u00c6\u00a9y g\u2030i l\u00b5 \u00c6\ufb01nh lu\u00c0t v\u201c c\u00b4ng : Kh\u00b4ng m\u00c8t m\u220fy c\u00a8 \u00c6\u00a8n gi\u2202n n\u00b5o cho ta l\u00d3i v\u201c c\u00b4ng. \u00df\u2260\u00d3c l\u00d3i bao nhi\u2122u l\u00abn v\u201c l\u02d8c th\u25ca l\u03c0i thi\u00f7t b\u2020y nhi\u2122u l\u00abn v\u201c \u00c6\u2260\u00cdng \u00c6i v\u00b5 ng\u2260\u00d3c l\u03c0i. III - V\u00c0n d\u00d9ng C5 K\u00e4o \u00c6\u201cu hai th\u00d4ng h\u00b5ng, m\u00c1i th\u00d4ng n\u2206ng 500N l\u2122n s\u00b5n \u00b4t\u00b4 c\u220fch m\u2206t \u00c6\u2020t 1m b\u00aang t\u2020m v\u220fn \u00c6\u2206t nghi\u2122ng (ma s\u220ft kh\u00b4ng \u00c6\u220fng k\u201d). K\u00e4o th\u00d4ng th\u00af nh\u2020t, d\u00d4ng t\u2020m v\u220fn d\u00b5i 4m. K\u00e4o th\u00d4ng th\u00af hai, d\u00d4ng t\u2020m v\u220fn d\u00b5i 2m. 50","H\u00b7i : a) Trong tr\u2260\u00cdng h\u00d3p n\u00b5o ng\u2260\u00cdi ta k\u00e4o v\u00cci l\u02d8c nh\u00b7 h\u00a8n v\u00b5 nh\u00b7 h\u00a8n bao nhi\u2122u l\u00abn ? b) Tr\u2260\u00cdng h\u00d3p n\u00b5o th\u25ca t\u00cbn nhi\u201cu c\u00b4ng h\u00a8n ? c) T\u203anh c\u00b4ng c\u00d2a l\u02d8c k\u00e4o th\u00d4ng h\u00b5ng theo m\u2206t ph\u00bang nghi\u2122ng l\u2122n s\u00b5n \u00b4t\u00b4. C6 \u00df\u201d \u00c6\u2260a m\u00c8t v\u00c0t c\u201e tr\u2030ng l\u2260\u00d3ng P = 420N l\u2122n cao theo ph\u2260\u00a8ng th\u00bang \u00c6\u00afng b\u00aang r\ufb02ng r\u2030c \u00c6\u00c8ng, theo h\u25canh 13.3, ng\u2260\u00cdi c\u00b4ng nh\u00a9n ph\u2202i k\u00e4o \u00c6\u00abu d\u00a9y \u00c6i m\u00c8t \u00c6o\u03c0n l\u00b5 8m. B\u00b7 qua ma s\u220ft. a) T\u203anh l\u02d8c k\u00e4o v\u00b5 \u00c6\u00c8 cao \u00c6\u2260a v\u00c0t l\u2122n. b) T\u203anh c\u00b4ng n\u00a9ng v\u00c0t l\u2122n. \u00df\ufb01nh lu\u00c0t v\u201c c\u00b4ng : Kh\u00b4ng m\u00c8t m\u220fy c\u00a8 \u00c6\u00a8n gi\u2202n n\u00b5o cho ta l\u00d3i v\u201c c\u00b4ng. \u00df\u2260\u00d3c l\u00d3i bao nhi\u2122u l\u00abn v\u201c l\u02d8c th\u25ca thi\u00f7t b\u2020y nhi\u2122u l\u00abn v\u201c \u00c6\u2260\u00cdng \u00c6i v\u00b5 ng\u2260\u00d3c l\u03c0i. C\u201e th\u201d em ch\u2260a bi\u2019t Trong th\u02d8c t\u2019, \u00ce c\u220fc m\u220fy c\u00a8 \u00c6\u00a8n gi\u2202n bao gi\u00cd c\u00dang c\u201e ma s\u220ft. V\u25ca v\u00c0y, c\u00b4ng m\u00b5 ta ph\u2202i t\u00cbn (A2) \u00c6\u201d n\u00a9ng v\u00c0t l\u2122n bao gi\u00cd c\u00dang l\u00ccn h\u00a8n c\u00b4ng (A1) d\u00d4ng \u00c6\u201d n\u00a9ng v\u00c0t khi kh\u00b4ng c\u201e ma s\u220ft, \u00c6\u201e l\u00b5 v\u25ca ph\u2202i t\u00cbn m\u00c8t ph\u00abn c\u00b4ng \u00c6\u201d th\u00e6ng ma s\u220ft. C\u00b4ng A2 l\u00b5 c\u00b4ng to\u00b5n ph\u00abn. C\u00b4ng A1 l\u00b5 c\u00b4ng c\u201e \u203ach. T\u00ff s\u00cb A1 g\u2030i l\u00b5 hi\u00f7u su\u2020t A2 c\u00d2a m\u220fy, k\u203a hi\u00f7u l\u00b5 H : A1 H = 100%. A2 V\u25ca A2 lu\u00b4n l\u00ccn h\u00a8n A1 n\u2122n hi\u00f7u su\u2020t lu\u00b4n nh\u00b7 h\u00a8n 100%. 51","B\u00b5i 15 C\u00b4ng su\u2020t I - Ai l\u00b5m vi\u00f7c kho\u0152 h\u00a8n ? Trong x\u00a9y d\u02d8ng, \u00c6\u201d \u00c6\u2260a v\u00c0t li\u00f7u l\u2122n cao ng\u2260\u00cdi ta th\u2260\u00cdng d\u00d4ng d\u00a9y k\u00e4o v\u00e6t qua r\ufb02ng r\u2030c c\u00cb \u00c6\ufb01nh nh\u2260 h\u25canh 15.1. Anh An v\u00b5 anh D\u00dang d\u00d4ng h\u00f7 th\u00cbng n\u00b5y \u00c6\u2260a g\u03c0ch l\u2122n t\u00abng hai, cao 4m, m\u00c1i vi\u2122n g\u03c0ch \u00c6\u201cu n\u2206ng 16N. M\u00c1i l\u00abn anh An k\u00e4o \u00c6\u2260\u00d3c 10 vi\u2122n g\u03c0ch m\u2020t 50 gi\u00a9y. C\ufb02n anh D\u00dang m\u00c1i l\u00abn k\u00e4o \u00c6\u2260\u00d3c 15 vi\u2122n g\u03c0ch m\u2020t 60 gi\u00a9y. C1 T\u203anh c\u00b4ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00d2a anh An v\u00b5 anh D\u00dang. C2 Trong c\u220fc ph\u2260\u00a8ng \u220fn sau \u00c6\u00a9y, c\u201e th\u201d ch\u2030n nh\u02dcng ph\u2260\u00a8ng \u220fn n\u00b5o \u00c6\u201d bi\u2019t ai l\u00b5 ng\u2260\u00cdi l\u00b5m vi\u00f7c kho\u0152 h\u00a8n ? a) So s\u220fnh c\u00b4ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00d2a hai H\u25canh 15.1 ng\u2260\u00cdi, ai th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00b4ng l\u00ccn h\u00a8n th\u25ca ng\u2260\u00cdi \u00c6\u201e l\u00b5m vi\u00f7c kho\u0152 h\u00a8n. b) So s\u220fnh th\u00cdi gian k\u00e4o g\u03c0ch l\u2122n cao c\u00d2a hai ng\u2260\u00cdi, ai l\u00b5m m\u2020t \u203at th\u00cdi gian h\u00a8n th\u25ca ng\u2260\u00cdi \u00c6\u201e l\u00b5m vi\u00f7c kho\u0152 h\u00a8n. c) So s\u220fnh th\u00cdi gian c\u00d2a hai ng\u2260\u00cdi \u00c6\u201d th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00d4ng m\u00c8t c\u00b4ng, ai l\u00b5m vi\u00f7c m\u2020t \u203at th\u00cdi gian h\u00a8n (th\u02d8c hi\u00f7n c\u00b4ng nhanh h\u00a8n) th\u25ca ng\u2260\u00cdi \u00c6\u201e l\u00b5m vi\u00f7c kho\u0152 h\u00a8n. d) So s\u220fnh c\u00b4ng c\u00d2a hai ng\u2260\u00cdi th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c trong c\u00d4ng m\u00c8t th\u00cdi gian, ai th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00b4ng l\u00ccn h\u00a8n th\u25ca ng\u2260\u00cdi \u00c6\u201e l\u00b5m vi\u00f7c kho\u0152 h\u00a8n. C3 T\u0131 k\u2019t qu\u2202 c\u00d2a C2, h\u2211y t\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a k\u2019t lu\u00c0n sau : Anh ....(1).... l\u00b5m vi\u00f7c kho\u0152 h\u00a8n, v\u25ca ....(2).... 52","II - C\u00b4ng su\u2020t Trong V\u00c0t l\u203a h\u2030c, \u00c6\u201d bi\u2019t ng\u2260\u00cdi n\u00b5o hay m\u220fy n\u00b5o th\u02d8c hi\u00f7n c\u00b4ng nhanh h\u00a8n (l\u00b5m vi\u00f7c kho\u0152 h\u00a8n) ng\u2260\u00cdi ta d\u00d4ng kh\u220fi ni\u00f7m c\u00b4ng su\u2020t. C\u00b4ng su\u2020t \u00c6\u2260\u00d3c x\u220fc \u00c6\ufb01nh b\u00aang c\u00b4ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c trong m\u00c8t \u00c6\u00a8n v\ufb01 th\u00cdi gian. N\u2019u trong th\u00cdi gian t, c\u00b4ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c l\u00b5 A th\u25ca c\u00b4ng su\u2020t l\u00b5 P. A P= t III - \u00df\u2022n v\ufb01 c\u00b4ng su\u2020t N\u2019u c\u00b4ng A l\u00b5 1J, th\u00cdi gian t l\u00b5 1s, th\u25ca c\u00b4ng su\u2020t l\u00b5 1J P = = 1J\/s (jun tr\u2122n gi\u00a9y). 1s \u00df\u00a8n v\ufb01 c\u00b4ng su\u2020t J\/s \u00c6\u2260\u00d3c g\u2030i l\u00b5 o\u220ft, k\u203a hi\u00f7u l\u00b5 W. 1W = 1J\/s. 1kW (kil\u00b4o\u220ft) = 1 000W. 1MW (m\u2122gao\u220ft) = 1 000kW = 1 000 000W. IV - V\u00c0n d\u00d9ng C4 T\u203anh c\u00b4ng su\u2020t c\u00d2a anh An v\u00b5 anh D\u00dang trong v\u203a d\u00d9 \u00ce \u00c6\u00abu b\u00b5i h\u2030c. C5 \u00df\u201d c\u00b5y m\u00c8t s\u00b5o \u00c6\u2020t, ng\u2260\u00cdi ta d\u00d4ng tr\u00a9u c\u00b5y th\u25ca m\u2020t 2 gi\u00cd, nh\u2260ng n\u2019u d\u00d4ng m\u220fy c\u00b5y B\u00b4ng Sen th\u25ca ch\u00ff m\u2020t 20 ph\u00dbt. H\u00b7i tr\u00a9u hay m\u220fy c\u00b5y c\u201e c\u00b4ng su\u2020t l\u00ccn h\u00a8n v\u00b5 l\u00ccn h\u00a8n bao nhi\u2122u l\u00abn ? C6 * M\u00c8t con ng\u02d8a k\u00e4o m\u00c8t c\u220fi xe \u00c6i \u00c6\u201cu v\u00cci v\u00c0n t\u00cbc 9km\/h. L\u02d8c k\u00e4o c\u00d2a ng\u02d8a l\u00b5 200N. a) T\u203anh c\u00b4ng su\u2020t c\u00d2a ng\u02d8a. b) Ch\u00afng minh r\u00aang P = F.v. 53","C\u00b4ng su\u2020t \u00c6\u2260\u00d3c x\u220fc \u00c6\ufb01nh b\u00aang c\u00b4ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c trong m\u00c8t \u00c6\u00a8n v\ufb01 th\u00cdi gian. A C\u00b4ng th\u00afc t\u203anh c\u00b4ng su\u2020t P = , trong \u00c6\u201e : A l\u00b5 c\u00b4ng th\u02d8c hi\u00f7n t \u00c6\u2260\u00d3c, t l\u00b5 th\u00cdi gian th\u02d8c hi\u00f7n c\u00b4ng \u00c6\u201e. \u00df\u00a8n v\ufb01 c\u00b4ng su\u2020t l\u00b5 o\u220ft, k\u203a hi\u00f7u l\u00b5 W. 1W = 1J\/s (jun tr\u2122n gi\u00a9y). 1kW (kil\u00b4o\u220ft) = 1 000W. 1MW (m\u2122gao\u220ft) = 1 000 000W. C\u201e th\u201d em ch\u2260a bi\u2019t \u00df\u201d \u00c6o c\u00b4ng su\u2020t, ngo\u00b5i o\u220ft, ng\u2260\u00cdi ta c\ufb02n d\u00d4ng \u00c6\u00a8n v\ufb01 kh\u220fc n\u02dca l\u00b5 m\u2211 l\u02d8c (s\u00afc ng\u02d8a). M\u2211 l\u02d8c l\u00b5 \u00c6\u00a8n v\ufb01 c\u00da \u00c6\u201d \u00c6o c\u00b4ng su\u2020t, tr\u2260\u00ccc \u00c6\u00a9y r\u2020t th\u00b4ng d\u00d9ng, nay \u203at d\u00d4ng. M\u00c8t m\u2211 l\u02d8c Ph\u220fp (k\u203a hi\u00f7u CV) x\u2020p x\u00ff b\u00aang 736W, c\ufb02n m\u00c8t m\u2211 l\u02d8c Anh (k\u203a hi\u00f7u l\u00b5 HP) x\u2020p x\u00ff b\u00aang 746W. C\u00b4ng su\u2020t c\u00d2a t\u2122n l\u02c6a \u00c6\u00bby con t\u00b5u v\u00da tr\u00d9 Ph\u2260\u00a8ng \u00df\u00b4ng ch\u00ce nh\u00b5 du h\u00b5nh v\u00da tr\u00d9 \u00c6\u00abu ti\u2122n c\u00d2a Tr\u220fi \u00df\u2020t Ga-ga-rin, c\u00b4ng d\u00a9n Li\u2122n X\u00b4 (tr\u2260\u00ccc \u00c6\u00a9y) l\u00b5 15 000MW. C\u00b4ng su\u2020t c\u00d2a con ng\u2260\u00cdi khi lao \u00c6\u00c8ng ch\u00a9n tay trong nh\u02dcng \u00c6i\u201cu ki\u00f7n b\u25canh th\u2260\u00cdng trung b\u25canh v\u00b5o kho\u2202ng t\u0131 70 \u00c6\u2019n 80W. Khi \u00c6i b\u00c8, c\u00b4ng su\u2020t trung b\u25canh c\u00d2a ng\u2260\u00cdi l\u00b5 300W. Khi ch\u03c0y thi 100m, c\u00b4ng su\u2020t c\u00d2a v\u00c0n \u00c6\u00c8ng vi\u2122n c\u201e th\u201d l\u2122n t\u00cci 730W. N\u2260\u00ccc ta c\u201e nhi\u201cu nh\u00b5 m\u220fy thu\u02da \u00c6i\u00f7n. Hi\u00f7n nay, nh\u00b5 m\u220fy thu\u02da \u00c6i\u00f7n Ho\u00b5 B\u25canh (c\u220fch H\u00b5 N\u00c8i kho\u2202ng 80km v\u201c ph\u203aa T\u00a9y) c\u201e c\u00b4ng su\u2020t l\u00ccn nh\u2020t l\u00b5 1 920MW. 54","B\u00b5i 16 C\u2022 N\u00b0NG H\u00b5ng ng\u00b5y, ta th\u2260\u00cdng nghe n\u201ei \u00c6\u2019n t\u0131 \\\"n\u00aeng l\u2260\u00d3ng\\\". V\u203a d\u00d9, nh\u00b5 m\u220fy thu\u02da \u00c6i\u00f7n Ho\u00b5 B\u25canh \u00c6\u2211 bi\u2019n n\u00aeng l\u2260\u00d3ng c\u00d2a d\ufb02ng n\u2260\u00ccc th\u00b5nh n\u00aeng l\u2260\u00d3ng \u00c6i\u00f7n. Con ng\u2260\u00cdi mu\u00cbn ho\u03c0t \u00c6\u00c8ng ph\u2202i c\u201e n\u00aeng l\u2260\u00d3ng. V\u00c0y n\u00aeng l\u2260\u00d3ng l\u00b5 g\u25ca ? N\u201e t\u00c2n t\u03c0i d\u2260\u00cci d\u03c0ng n\u00b5o ? Trong b\u00b5i n\u00b5y, ch\u00dbng ta s\u0153 t\u25cam hi\u201du d\u03c0ng n\u00aeng l\u2260\u00d3ng \u00c6\u00a8n gi\u2202n nh\u2020t l\u00b5 c\u00a8 n\u00aeng. I - C\u00a8 n\u00aeng - Khi m\u00c8t v\u00c0t c\u201e kh\u2202 n\u00aeng th\u02d8c hi\u00f7n c\u00b4ng c\u00a8 h\u2030c, ta n\u201ei v\u00c0t \u00c6\u201e c\u201e c\u00a8 n\u00aeng. - V\u00c0t c\u201e kh\u2202 n\u00aeng th\u02d8c hi\u00f7n c\u00b4ng c\u00a8 h\u2030c c\u00b5ng l\u00ccn th\u25ca c\u00a8 n\u00aeng c\u00d2a v\u00c0t c\u00b5ng l\u00ccn. C\u00a8 n\u00aeng c\u00dang \u00c6\u2260\u00d3c \u00c6o b\u00aang \u00c6\u00a8n v\ufb01 jun. II - Th\u2019 n\u00aeng a) 1. Th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng b) H\u25canh 16.1 Qu\u2202 n\u2206ng A \u00c6\u00afng y\u2122n tr\u2122n m\u2206t \u00c6\u2020t (H.16.1a), kh\u00b4ng c\u201e kh\u2202 n\u00aeng sinh c\u00b4ng. 55 C1 N\u2019u \u00c6\u2260a qu\u2202 n\u2206ng l\u2122n m\u00c8t \u00c6\u00c8 cao n\u00b5o \u00c6\u201e (H.16.1b) th\u25ca n\u201e c\u201e c\u00a8 n\u00aeng kh\u00b4ng ? T\u03c0i sao ? C\u00a8 n\u00aeng c\u00d2a v\u00c0t trong tr\u2260\u00cdng h\u00d3p n\u00b5y \u00c6\u2260\u00d3c g\u2030i l\u00b5 th\u2019 n\u00aeng. V\u00c0t \u00ce v\ufb01 tr\u203a c\u00b5ng cao so v\u00cci m\u2206t \u00c6\u2020t th\u25ca c\u00b4ng m\u00b5 v\u00c0t c\u201e kh\u2202 n\u00aeng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00b5ng l\u00ccn, ngh\u2039a l\u00b5 th\u2019 n\u00aeng c\u00d2a v\u00c0t c\u00b5ng l\u00ccn. Th\u2019 n\u00aeng \u00c6\u2260\u00d3c x\u220fc \u00c6\ufb01nh b\u00cei \u00c6\u00c8 cao c\u00d2a v\u00c0t so v\u00cci m\u2206t \u00c6\u2020t g\u2030i l\u00b5 th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng. Khi v\u00c0t n\u00aam tr\u2122n m\u2206t \u00c6\u2020t th\u25ca th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng c\u00d2a v\u00c0t b\u00aang kh\u00b4ng.","Ch\u00db \u02dd : - Ta c\u201e th\u201d kh\u00b4ng l\u2020y m\u2206t \u00c6\u2020t, m\u00b5 l\u2020y m\u00c8t v\ufb01 tr\u203a kh\u220fc l\u00b5m m\u00cbc \u00c6\u201d t\u203anh \u00c6\u00c8 cao. V\u00c0y th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng ph\u00d9 thu\u00c8c v\u00b5o m\u00cbc t\u203anh \u00c6\u00c8 cao. - Th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng c\u00d2a v\u00c0t c\ufb02n ph\u00d9 thu\u00c8c v\u00b5o kh\u00cbi l\u2260\u00d3ng c\u00d2a n\u201e. V\u00c0t c\u201e kh\u00cbi l\u2260\u00d3ng c\u00b5ng l\u00ccn th\u25ca th\u2019 n\u00aeng c\u00b5ng l\u00ccn. 2. Th\u2019 n\u00aeng \u00c6\u00b5n h\u00c2i a) b) H\u25canh 16.2 C\u201e m\u00c8t l\ufb02 xo \u00c6\u2260\u00d3c l\u00b5m b\u00aang b\u00aeng th\u00e4p u\u00cbn th\u00b5nh v\ufb02ng tr\ufb02n (H.16.2a). L\ufb02 xo b\ufb01 n\u00e4n l\u03c0i nh\u00cd bu\u00c8c s\u00d3i d\u00a9y, ph\u203aa tr\u2122n \u00c6\u2206t m\u00c8t mi\u2019ng g\u00c1 (H.16.2b). C2 L\u00dbc n\u00b5y l\ufb02 xo c\u201e c\u00a8 n\u00aeng. B\u00aang c\u220fch n\u00b5o \u00c6\u201d bi\u2019t \u00c6\u2260\u00d3c l\ufb02 xo c\u201e c\u00a8 n\u00aeng ? C\u00a8 n\u00aeng c\u00d2a l\ufb02 xo trong tr\u2260\u00cdng h\u00d3p n\u00b5y c\u00dang \u00c6\u2260\u00d3c g\u2030i l\u00b5 th\u2019 n\u00aeng. L\ufb02 xo c\u00b5ng b\ufb01 n\u00e4n nhi\u201cu th\u25ca c\u00b4ng do l\ufb02 xo sinh ra c\u00b5ng l\u00ccn, ngh\u2039a l\u00b5 th\u2019 n\u00aeng c\u00d2a l\ufb02 xo c\u00b5ng l\u00ccn. V\u25ca th\u2019 n\u00aeng n\u00b5y ph\u00d9 thu\u00c8c v\u00b5o \u00c6\u00c8 bi\u2019n d\u03c0ng \u00c6\u00b5n h\u00c2i, n\u2122n \u00c6\u2260\u00d3c g\u2030i l\u00b5 th\u2019 n\u00aeng \u00c6\u00b5n h\u00c2i. III - \u00df\u00c8ng n\u00aeng 1. Khi n\u00b5o v\u00c0t c\u201e \u00c6\u00c8ng n\u00aeng ? Th\u203a nghi\u00f7m 1 Cho qu\u2202 c\u00abu A b\u00aang th\u00e4p l\u00aen t\u0131 v\ufb01 tr\u203a (1) tr\u2122n m\u220fng nghi\u2122ng xu\u00cbng \u00c6\u00c0p v\u00b5o mi\u2019ng g\u00c1 B (H.16.3). C3 Hi\u00f7n t\u2260\u00d3ng s\u0153 x\u2202y ra nh\u2260 th\u2019 n\u00b5o ? C4 Ch\u00afng minh r\u00aang qu\u2202 c\u00abu A H\u25canh 16.3 \u00c6ang chuy\u201dn \u00c6\u00c8ng c\u201e kh\u2202 n\u00aeng th\u02d8c hi\u00f7n c\u00b4ng. C5 T\u0131 k\u2019t qu\u2202 th\u203a nghi\u00f7m h\u2211y t\u25cam t\u0131 th\u203ach h\u00d3p cho ch\u00c1 tr\u00cbng c\u00d2a k\u2019t lu\u00c0n : M\u00c8t v\u00c0t chuy\u201dn \u00c6\u00c8ng c\u201e kh\u2202 n\u00aeng ........ t\u00afc l\u00b5 c\u201e c\u00a8 n\u00aeng. C\u00a8 n\u00aeng c\u00d2a v\u00c0t do chuy\u201dn \u00c6\u00c8ng m\u00b5 c\u201e \u00c6\u2260\u00d3c g\u2030i l\u00b5 \u00c6\u00c8ng n\u00aeng. 56","2. \u00df\u00c8ng n\u00aeng c\u00d2a v\u00c0t ph\u00d9 thu\u00c8c nh\u02dcng y\u2019u t\u00cb n\u00b5o ? Th\u203a nghi\u00f7m 2 Cho qu\u2202 c\u00abu A l\u00aen tr\u2122n m\u220fng nghi\u2122ng t\u0131 v\ufb01 tr\u203a (2) cao h\u00a8n v\ufb01 tr\u203a (1) (H.16.3) t\u00cci \u00c6\u00c0p v\u00b5o mi\u2019ng g\u00c1 B. C6 \u00df\u00c8 l\u00ccn v\u00c0n t\u00cbc c\u00d2a qu\u2202 c\u00abu l\u00dbc \u00c6\u00c0p v\u00b5o mi\u2019ng g\u00c1 B thay \u00c6\u00cai th\u2019 n\u00b5o so v\u00cci th\u203a nghi\u00f7m 1 ? So s\u220fnh c\u00b4ng c\u00d2a qu\u2202 c\u00abu A th\u02d8c hi\u00f7n l\u00dbc n\u00b5y v\u00cci l\u00dbc tr\u2260\u00ccc. T\u0131 \u00c6\u201e suy ra \u00c6\u00c8ng n\u00aeng c\u00d2a qu\u2202 c\u00abu A ph\u00d9 thu\u00c8c th\u2019 n\u00b5o v\u00b5o v\u00c0n t\u00cbc c\u00d2a n\u201e ? Th\u203a nghi\u00f7m 3 Thay qu\u2202 c\u00abu A b\u00aang qu\u2202 c\u00abu A' c\u201e kh\u00cbi l\u2260\u00d3ng l\u00ccn h\u00a8n v\u00b5 cho l\u00aen tr\u2122n m\u220fng nghi\u2122ng t\u0131 v\ufb01 tr\u203a (2), \u00c6\u00c0p v\u00b5o mi\u2019ng g\u00c1 B. C7 Hi\u00f7n t\u2260\u00d3ng x\u2202y ra c\u201e g\u25ca kh\u220fc so v\u00cci th\u203a nghi\u00f7m 2 ? So s\u220fnh c\u00b4ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c c\u00d2a hai qu\u2202 c\u00abu A v\u00b5 A'. T\u0131 \u00c6\u201e suy ra \u00c6\u00c8ng n\u00aeng c\u00d2a qu\u2202 c\u00abu c\ufb02n ph\u00d9 thu\u00c8c th\u2019 n\u00b5o v\u00b5o kh\u00cbi l\u2260\u00d3ng c\u00d2a n\u201e. C8 C\u220fc th\u203a nghi\u00f7m tr\u2122n cho th\u2020y \u00c6\u00c8ng n\u00aeng ph\u00d9 thu\u00c8c nh\u02dcng y\u2019u t\u00cb g\u25ca v\u00b5 ph\u00d9 thu\u00c8c th\u2019 n\u00b5o ? Ch\u00db \u02dd : \u00df\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng l\u00b5 hai d\u03c0ng c\u00d2a c\u00a8 n\u00aeng. M\u00c8t v\u00c0t c\u201e th\u201d v\u0131a c\u201e \u00c6\u00c8ng n\u00aeng v\u0131a c\u201e th\u2019 n\u00aeng. C\u00a8 n\u00aeng c\u00d2a v\u00c0t l\u00dbc \u00c6\u201e b\u00aang t\u00cang \u00c6\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng c\u00d2a n\u201e. IV - V\u00c0n d\u00d9ng C9 N\u2122u v\u203a d\u00d9 v\u00c0t c\u201e c\u2202 \u00c6\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng. C10 C\u00a8 n\u00aeng c\u00d2a t\u0131ng v\u00c0t \u00ce h\u25canh 16.4a, b, c thu\u00c8c d\u03c0ng c\u00a8 n\u00aeng n\u00b5o ? a) Chi\u2019c cung \u00c6\u2211 b) N\u2260\u00ccc ch\u2202y t\u0131 c) N\u2260\u00ccc b\ufb01 ng\u00aen \u00c6\u2260\u00d3c gi\u2260\u00a8ng. tr\u2122n cao xu\u00cbng. tr\u2122n \u00c6\u00c0p cao. H\u25canh 16.4 57","Khi v\u00c0t c\u201e kh\u2202 n\u00aeng sinh c\u00b4ng, ta n\u201ei v\u00c0t c\u201e c\u00a8 n\u00aeng. C\u00a8 n\u00aeng c\u00d2a v\u00c0t ph\u00d9 thu\u00c8c v\u00b5o \u00c6\u00c8 cao c\u00d2a v\u00c0t so v\u00cci m\u2206t \u00c6\u2020t, ho\u2206c so v\u00cci m\u00c8t v\ufb01 tr\u203a kh\u220fc \u00c6\u2260\u00d3c ch\u2030n l\u00b5m m\u00cbc \u00c6\u201d t\u203anh \u00c6\u00c8 cao, g\u2030i l\u00b5 th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng. V\u00c0t c\u201e kh\u00cbi l\u2260\u00d3ng c\u00b5ng l\u00ccn v\u00b5 \u00ce c\u00b5ng cao th\u25ca th\u2019 n\u00aeng tr\u2030ng tr\u2260\u00cdng c\u00d2a v\u00c0t c\u00b5ng l\u00ccn. C\u00a8 n\u00aeng c\u00d2a v\u00c0t ph\u00d9 thu\u00c8c v\u00b5o \u00c6\u00c8 bi\u2019n d\u03c0ng c\u00d2a v\u00c0t g\u2030i l\u00b5 th\u2019 n\u00aeng \u00c6\u00b5n h\u00c2i. C\u00a8 n\u00aeng c\u00d2a v\u00c0t do chuy\u201dn \u00c6\u00c8ng m\u00b5 c\u201e g\u2030i l\u00b5 \u00c6\u00c8ng n\u00aeng. V\u00c0t c\u201e kh\u00cbi l\u2260\u00d3ng c\u00b5ng l\u00ccn v\u00b5 chuy\u201dn \u00c6\u00c8ng c\u00b5ng nhanh th\u25ca \u00c6\u00c8ng n\u00aeng c\u00b5ng l\u00ccn. \u00df\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng l\u00b5 hai d\u03c0ng c\u00d2a c\u00a8 n\u00aeng. C\u00a8 n\u00aeng c\u00d2a m\u00c8t v\u00c0t b\u00aang t\u00cang th\u2019 n\u00aeng v\u00b5 \u00c6\u00c8ng n\u00aeng c\u00d2a n\u201e. C\u201e th\u201d em ch\u2260a bi\u2019t 2,7.1033J. 3.109J. \u00df\u00c8 l\u00ccn c\u00d2a m\u00c8t s\u00cb gi\u220f tr\ufb01 \u00c6\u00c8ng n\u00aeng 4 500J. - \u00df\u00c8ng n\u00aeng c\u00d2a Tr\u220fi \u00df\u2020t chuy\u201dn \u00c6\u00c8ng quanh M\u2206t Tr\u00cdi : 0,002J. - \u00df\u00c8ng n\u00aeng c\u00d2a v\u00f7 tinh quay tr\u2122n qu\u00b8 \u00c6\u03c0o : - \u00df\u00c8ng n\u00aeng c\u00d2a c\u00abu th\u00d2 b\u201eng \u00c6\u220f \u00c6ang ch\u03c0y : 0,0000001J. - \u00df\u00c8ng n\u00aeng c\u00d2a con ong \u00c6ang bay : - \u00df\u00c8ng n\u00aeng c\u00d2a con s\u2122n \u00c6ang b\ufb02 : (Ch\u00db \u02dd : C\u220fc \u00c6\u00c8 l\u00ccn ghi \u00ce tr\u2122n ch\u00ff g\u00abn \u00c6\u00dbng). 58","B\u00b5i 17 S# CHUY\u00d5N Ho\u220f V\u00c4 B\u00c5O TO\u00c4N C\u2022 N\u00b0NG Trong t\u02d8 nhi\u2122n c\u00dang nh\u2260 trong k\u2039 thu\u00c0t, ta th\u2260\u00cdng quan s\u220ft th\u2020y s\u02d8 chuy\u201dn ho\u220f c\u00a8 n\u00aeng t\u0131 d\u03c0ng n\u00b5y sang d\u03c0ng kh\u220fc : \u00df\u00c8ng n\u00aeng chuy\u201dn ho\u220f th\u00b5nh th\u2019 n\u00aeng v\u00b5 ng\u2260\u00d3c l\u03c0i th\u2019 n\u00aeng chuy\u201dn ho\u220f th\u00b5nh \u00c6\u00c8ng n\u00aeng. D\u2260\u00cci \u00c6\u00a9y ta s\u0153 kh\u2202o s\u220ft c\u00d9 th\u201d s\u02d8 chuy\u201dn ho\u220f n\u00b5y. I - S\u02d8 chuy\u201dn ho\u220f c\u00d2a c\u220fc d\u03c0ng c\u00a8 n\u00aeng H\u25canh 17.1 59 Th\u203a nghi\u00f7m 1 : Qu\u2202 b\u201eng r\u00a8i H\u25canh 17.1 ghi l\u03c0i v\ufb01 tr\u203a c\u00d2a qu\u2202 b\u201eng \u00c6ang r\u00a8i sau nh\u02dcng kho\u2202ng th\u00cdi gian b\u00aang nhau. C1 \u00df\u00c8 cao v\u00b5 v\u00c0n t\u00cbc c\u00d2a qu\u2202 b\u201eng thay \u00c6\u00cai th\u2019 n\u00b5o trong th\u00cdi gian qu\u2202 b\u201eng r\u00a8i ? T\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a c\u00a9u tr\u2202 l\u00cdi sau : Trong th\u00cdi gian qu\u2202 b\u201eng r\u00a8i, \u00c6\u00c8 cao c\u00d2a qu\u2202 b\u201eng ....(1).... d\u00abn, v\u00c0n t\u00cbc c\u00d2a qu\u2202 b\u201eng ....(2).... d\u00abn. C2 Th\u2019 n\u00aeng v\u00b5 \u00c6\u00c8ng n\u00aeng c\u00d2a qu\u2202 b\u201eng thay \u00c6\u00cai th\u2019 n\u00b5o ? T\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a c\u00a9u tr\u2202 l\u00cdi sau : Th\u2019 n\u00aeng c\u00d2a qu\u2202 b\u201eng ....(1).... d\u00abn, c\ufb02n \u00c6\u00c8ng n\u00aeng c\u00d2a n\u201e ....(2).... C3 Khi qu\u2202 b\u201eng ch\u03c0m m\u2206t \u00c6\u2020t, n\u201e n\u2202y l\u2122n. Trong th\u00cdi gian n\u2202y l\u2122n, \u00c6\u00c8 cao v\u00b5 v\u00c0n t\u00cbc c\u00d2a qu\u2202 b\u201eng thay \u00c6\u00cai th\u2019 n\u00b5o ? Th\u2019 n\u00aeng v\u00b5 \u00c6\u00c8ng n\u00aeng c\u00d2a n\u201e thay \u00c6\u00cai th\u2019 n\u00b5o ? T\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a c\u00a9u tr\u2202 l\u00cdi sau : Trong th\u00cdi gian n\u2202y l\u2122n, \u00c6\u00c8 cao c\u00d2a qu\u2202 b\u201eng ....(1).... d\u00abn, v\u00c0n t\u00cbc c\u00d2a n\u201e ....(2).... d\u00abn. Nh\u2260 v\u00c0y th\u2019 n\u00aeng c\u00d2a qu\u2202 b\u201eng ....(3).... d\u00abn, \u00c6\u00c8ng n\u00aeng c\u00d2a n\u201e ....(4).... d\u00abn. C4 \u00f4 nh\u02dcng v\ufb01 tr\u203a n\u00b5o (A hay B) qu\u2202 b\u201eng c\u201e th\u2019 n\u00aeng, \u00c6\u00c8ng n\u00aeng l\u00ccn nh\u2020t ; c\u201e th\u2019 n\u00aeng, \u00c6\u00c8ng n\u00aeng nh\u00b7 nh\u2020t ? T\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a c\u220fc c\u00a9u tr\u2202 l\u00cdi sau :","Qu\u2202 b\u201eng c\u201e th\u2019 n\u00aeng l\u00ccn nh\u2020t khi \u00ce v\ufb01 tr\u203a ....(1).... v\u00b5 c\u201e th\u2019 n\u00aeng nh\u00b7 nh\u2020t khi \u00ce v\ufb01 tr\u203a ....(2).... Qu\u2202 b\u201eng c\u201e \u00c6\u00c8ng n\u00aeng l\u00ccn nh\u2020t khi \u00ce v\ufb01 tr\u203a ....(3).... v\u00b5 \u00c6\u00c8ng n\u00aeng nh\u00b7 nh\u2020t khi \u00ce v\ufb01 tr\u203a ....(4).... Th\u203a nghi\u00f7m 2 : Con l\u00e6c dao \u00c6\u00c8ng H\u25canh 17.2 K\u00e4o con l\u00e6c l\u00f7ch kh\u00b7i v\ufb01 tr\u203a c\u00a9n b\u00aang t\u00cci v\ufb01 tr\u203a A r\u00c2i th\u2202 tay ra. Quan s\u220ft chuy\u201dn \u00c6\u00c8ng c\u00d2a con l\u00e6c (H.17.2). Con l\u00e6c c\u201e \u00c6\u00c8 cao l\u00ccn nh\u2020t \u00ce A v\u00b5 C, th\u2020p nh\u2020t \u00ce v\ufb01 tr\u203a c\u00a9n b\u00aang B. Ta l\u2020y v\ufb01 tr\u203a c\u00a9n b\u00aang B l\u00b5m m\u00cbc \u00c6\u201d t\u203anh c\u220fc \u00c6\u00c8 cao. C5 V\u00c0n t\u00cbc c\u00d2a con l\u00e6c t\u00aeng hay gi\u2202m khi : a) Con l\u00e6c \u00c6i t\u0131 A xu\u00cbng B. b) Con l\u00e6c \u00c6i t\u0131 B l\u2122n C. C6 C\u201e s\u02d8 chuy\u201dn ho\u220f t\u0131 d\u03c0ng c\u00a8 n\u00aeng n\u00b5o sang d\u03c0ng c\u00a8 n\u00aeng n\u00b5o khi : a) Con l\u00e6c \u00c6i t\u0131 A xu\u00cbng B ? b) Con l\u00e6c \u00c6i t\u0131 B l\u2122n C ? C7 \u00f4 nh\u02dcng v\ufb01 tr\u203a n\u00b5o con l\u00e6c c\u201e th\u2019 n\u00aeng l\u00ccn nh\u2020t, c\u201e \u00c6\u00c8ng n\u00aeng l\u00ccn nh\u2020t ? C8 \u00f4 nh\u02dcng v\ufb01 tr\u203a n\u00b5o con l\u00e6c c\u201e \u00c6\u00c8ng n\u00aeng nh\u00b7 nh\u2020t, c\u201e th\u2019 n\u00aeng nh\u00b7 nh\u2020t ? C\u220fc gi\u220f tr\ufb01 nh\u00b7 nh\u2020t n\u00b5y b\u00aang bao nhi\u2122u ? K\u2019t lu\u00c0n - Trong chuy\u201dn \u00c6\u00c8ng c\u00d2a con l\u00e6c \u00c6\u2211 c\u201e s\u02d8 chuy\u201dn ho\u220f li\u2122n t\u00d9c c\u220fc d\u03c0ng c\u00a8 n\u00aeng : Th\u2019 n\u00aeng chuy\u201dn ho\u220f th\u00b5nh \u00c6\u00c8ng n\u00aeng v\u00b5 \u00c6\u00c8ng n\u00aeng chuy\u201dn ho\u220f th\u00b5nh th\u2019 n\u00aeng. - Khi con l\u00e6c \u00ce v\ufb01 tr\u203a th\u2020p nh\u2020t (v\ufb01 tr\u203a c\u00a9n b\u00aang), th\u2019 n\u00aeng \u00c6\u2211 chuy\u201dn ho\u220f ho\u00b5n to\u00b5n th\u00b5nh \u00c6\u00c8ng n\u00aeng ; khi con l\u00e6c \u00ce v\ufb01 tr\u203a cao nh\u2020t, \u00c6\u00c8ng n\u00aeng \u00c6\u2211 chuy\u201dn ho\u220f ho\u00b5n to\u00b5n th\u00b5nh th\u2019 n\u00aeng. 60","II - b\u2202o to\u00b5n c\u00a8 n\u00aeng Nh\u02dcng th\u203a nghi\u00f7m \u00c6\ufb01nh l\u2260\u00d3ng ch\u203anh x\u220fc \u00c6\u2211 ch\u00afng t\u00b7 : Trong qu\u220f tr\u25canh c\u00a8 h\u2030c, \u00c6\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng c\u201e th\u201d chuy\u201dn ho\u220f l\u2026n nhau, nh\u2260ng c\u00a8 n\u00aeng th\u25ca kh\u00b4ng \u00c6\u00cai. Ng\u2260\u00cdi ta n\u201ei c\u00a8 n\u00aeng \u00c6\u2260\u00d3c b\u2202o to\u00b5n. Ch\u00db \u02dd : Khi m\u00b4 t\u2202 c\u220fc th\u203a nghi\u00f7m v\u0153 \u00ce h\u25canh 17.1 v\u00b5 17.2 ch\u00dbng ta \u00c6\u2211 b\u00b7 qua ma s\u220ft. Th\u02d8c ra, do c\u201e ma s\u220ft n\u2122n qu\u2202 b\u201eng sau khi ch\u03c0m \u00c6\u2020t kh\u00b4ng th\u201d n\u2202y tr\u00ce l\u03c0i \u00c6\u00c8 cao ban \u00c6\u00abu, c\u00dang nh\u2260 con l\u00e6c sau khi \u00c6\u2211 \u00c6\u2260\u00d3c th\u2202 ra \u00ce v\ufb01 tr\u203a A kh\u00b4ng th\u201d quay tr\u00ce l\u03c0i \u00c6\u00dbng v\ufb01 tr\u203a n\u00b5y. \u00dfi\u201cu \u00c6\u201e c\u201e ngh\u2039a l\u00b5, n\u2019u k\u201d \u00c6\u2019n ma s\u220ft, th\u25ca c\u00a8 n\u00aeng c\u00d2a v\u00c0t kh\u00b4ng b\u2202o to\u00b5n. M\u00c8t ph\u00abn c\u00a8 n\u00aeng \u00c6\u2211 chuy\u201dn ho\u220f th\u00b5nh m\u00c8t d\u03c0ng n\u00aeng l\u2260\u00d3ng kh\u220fc m\u00b5 ch\u00dbng ta s\u0153 h\u2030c trong c\u220fc b\u00b5i sau. III - V\u00c0n d\u00d9ng C9 H\u2211y ch\u00ff ra s\u02d8 chuy\u201dn ho\u220f t\u0131 d\u03c0ng c\u00a8 n\u00aeng n\u00b5y sang d\u03c0ng c\u00a8 n\u00aeng kh\u220fc trong c\u220fc tr\u2260\u00cdng h\u00d3p sau : a) M\u00dai t\u2122n \u00c6\u2260\u00d3c b\u00e6n \u00c6i t\u0131 chi\u2019c cung. b) N\u2260\u00ccc t\u0131 tr\u2122n \u00c6\u00c0p cao ch\u2202y xu\u00cbng. c) N\u00e4m m\u00c8t v\u00c0t l\u2122n cao theo ph\u2260\u00a8ng th\u00bang \u00c6\u00afng. \u00df\u00c8ng n\u00aeng c\u201e th\u201d chuy\u201dn ho\u220f th\u00b5nh th\u2019 n\u00aeng, ng\u2260\u00d3c l\u03c0i th\u2019 n\u00aeng c\u201e th\u201d chuy\u201dn ho\u220f th\u00b5nh \u00c6\u00c8ng n\u00aeng. Trong qu\u220f tr\u25canh c\u00a8 h\u2030c, \u00c6\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng c\u201e th\u201d chuy\u201dn ho\u220f l\u2026n nhau, nh\u2260ng c\u00a8 n\u00aeng \u00c6\u2260\u00d3c b\u2202o to\u00b5n. C\u201e th\u201d em ch\u2260a bi\u2019t C\u220fc ngu\u00c2n n\u2260\u00ccc \u00ce tr\u2122n cao c\u201e th\u2019 n\u00aeng r\u2020t l\u00ccn. Th\u2019 n\u00aeng n\u00b5y c\u201e th\u201d chuy\u201dn ho\u220f th\u00b5nh \u00c6\u00c8ng n\u00aeng l\u00b5m quay c\u220fc m\u220fy ph\u220ft \u00c6i\u00f7n. Hi\u00f7n nay, ng\u2260\u00cdi ta m\u00cci s\u02c6 d\u00d9ng \u00c6\u2260\u00d3c ch\u2260a t\u00cci 10% ngu\u00c2n n\u00aeng l\u2260\u00d3ng d\u02d8 tr\u02dc kh\u00cang l\u00c2 n\u00b5y. Gi\u201e c\u201e \u00c6\u00c8ng n\u00aeng r\u2020t l\u00ccn, l\u00b5 ngu\u00c2n n\u00aeng l\u2260\u00d3ng s\u03c0ch v\u00b5 r\u0152 ti\u201cn. N\u2019u con ng\u2260\u00cdi t\u00c0n d\u00d9ng \u00c6\u2260\u00d3c h\u2019t \u00c6\u00c8ng n\u00aeng c\u00d2a gi\u201e th\u25ca gi\u201e c\u201e th\u201d cung c\u2020p cho con ng\u2260\u00cdi n\u00aeng l\u2260\u00d3ng c\ufb02n l\u00ccn h\u00a8n n\u00aeng l\u2260\u00d3ng do n\u2260\u00ccc cung c\u2020p. T\u0131 x\u2260a, ng\u2260\u00cdi ta \u00c6\u2211 bi\u2019t s\u02c6 d\u00d9ng \u00c6\u00c8ng n\u00aeng c\u00d2a gi\u201e \u00c6\u201d ch\u03c0y c\u220fc c\u00cbi xay, g\u2030i l\u00b5 c\u00cbi xay H\u25canh 17.3 gi\u201e. \u00df\u00c0p thu\u02da \u00c6i\u00f7n Ho\u00b5 B\u25canh. 61","B\u00b5i 18 C\u00a9u h\u00b7i v\u00b5 b\u00b5i t\u00c0p t\u00cang k\u2019t CH\u00b6\u2022NG I : c\u00a8 h\u2030c A - \u00a7n t\u00c0p 1. Chuy\u201dn \u00c6\u00c8ng c\u00a8 h\u2030c l\u00b5 g\u25ca ? Cho a) V\u00c0t \u00c6ang \u00c6\u00afng y\u2122n ? hai v\u203a d\u00d9. b) V\u00c0t \u00c6ang chuy\u201dn \u00c6\u00c8ng ? 2. N\u2122u m\u00c8t v\u203a d\u00d9 ch\u00afng t\u00b7 m\u00c8t v\u00c0t 8. L\u02d8c ma s\u220ft xu\u2020t hi\u00f7n khi n\u00b5o ? c\u201e th\u201d chuy\u201dn \u00c6\u00c8ng so v\u00cci v\u00c0t N\u2122u hai v\u203a d\u00d9 v\u201c l\u02d8c ma s\u220ft. n\u00b5y, nh\u2260ng l\u03c0i \u00c6\u00afng y\u2122n so v\u00cci v\u00c0t kh\u220fc. 9. N\u2122u hai v\u203a d\u00d9 ch\u00afng t\u00b7 v\u00c0t c\u201e qu\u220fn t\u203anh. 3. \u00df\u00c8 l\u00ccn c\u00d2a v\u00c0n t\u00cbc \u00c6\u2206c tr\u2260ng cho t\u203anh ch\u2020t n\u00b5o c\u00d2a chuy\u201dn \u00c6\u00c8ng ? 10. T\u220fc d\u00d9ng c\u00d2a \u220fp l\u02d8c ph\u00d9 thu\u00c8c C\u00b4ng th\u00afc t\u203anh v\u00c0n t\u00cbc ? \u00df\u00a8n v\ufb01 nh\u02dcng y\u2019u t\u00cb n\u00b5o ? C\u00b4ng th\u00afc v\u00c0n t\u00cbc ? t\u203anh \u220fp su\u2020t. \u00df\u00a8n v\ufb01 \u220fp su\u2020t. 4. Chuy\u201dn \u00c6\u00c8ng kh\u00b4ng \u00c6\u201cu l\u00b5 g\u25ca ? 11. M\u00c8t v\u00c0t nh\u00dbng ch\u25cam trong ch\u2020t Vi\u2019t c\u00b4ng th\u00afc t\u203anh v\u00c0n t\u00cbc trung l\u00b7ng ch\ufb01u t\u220fc d\u00d9ng c\u00d2a m\u00c8t l\u02d8c b\u25canh c\u00d2a chuy\u201dn \u00c6\u00c8ng kh\u00b4ng \u00c6\u201cu. \u00c6\u00bby c\u201e ph\u2260\u00a8ng, chi\u201cu v\u00b5 \u00c6\u00c8 l\u00ccn nh\u2260 th\u2019 n\u00b5o ? 5. L\u02d8c c\u201e t\u220fc d\u00d9ng nh\u2260 th\u2019 n\u00b5o \u00c6\u00cbi v\u00cci v\u00c0n t\u00cbc ? N\u2122u v\u203a d\u00d9 minh ho\u03c0. 12. \u00dfi\u201cu ki\u00f7n \u00c6\u201d m\u00c8t v\u00c0t ch\u25cam xu\u00cbng, n\u00cai l\u2122n, l\u00a8 l\u02c6ng trong ch\u2020t l\u00b7ng. 6. N\u2122u c\u220fc y\u2019u t\u00cb c\u00d2a l\u02d8c v\u00b5 c\u220fch bi\u201du di\u2018n l\u02d8c b\u00aang vect\u00a8. 13. Trong khoa h\u2030c th\u25ca thu\u00c0t ng\u02dc c\u00b4ng c\u00a8 h\u2030c ch\u00ff d\u00d4ng trong tr\u2260\u00cdng 7. Th\u2019 n\u00b5o l\u00b5 hai l\u02d8c c\u00a9n b\u00aang ? M\u00c8t h\u00d3p n\u00b5o ? v\u00c0t ch\ufb01u t\u220fc d\u00d9ng c\u00d2a c\u220fc l\u02d8c c\u00a9n b\u00aang s\u0153 th\u2019 n\u00b5o khi : 14. Vi\u2019t bi\u201du th\u00afc t\u203anh c\u00b4ng c\u00a8 h\u2030c. Gi\u2202i th\u203ach r\u201a t\u0131ng \u00c6\u03c0i l\u2260\u00d3ng trong 62 bi\u201du th\u00afc t\u203anh c\u00b4ng. \u00df\u00a8n v\ufb01 c\u00b4ng.","15. Ph\u220ft bi\u201du \u00c6\ufb01nh lu\u00c0t v\u201c c\u00b4ng. 3. M\u00c8t \u00c6o\u00b5n m\u00b4t\u00b4 chuy\u201dn \u00c6\u00c8ng c\u00d4ng 16. C\u00b4ng su\u2020t cho ta bi\u2019t \u00c6i\u201cu g\u25ca ? chi\u201cu, c\u00d4ng v\u00c0n t\u00cbc \u00c6i ngang qua m\u00c8t \u00b4t\u00b4 \u00c6\u00c1 b\u2122n \u00c6\u2260\u00cdng. \u2265 ki\u2019n 17. Th\u2019 n\u00b5o l\u00b5 s\u02d8 b\u2202o to\u00b5n c\u00a8 n\u00aeng ? nh\u00c0n x\u00e4t n\u00b5o sau \u00c6\u00a9y l\u00b5 \u00c6\u00dbng ? N\u2122u ba v\u203a d\u00d9 v\u201c s\u02d8 chuy\u201dn ho\u220f t\u0131 d\u03c0ng c\u00a8 n\u00aeng n\u00b5y sang d\u03c0ng c\u00a8 A. C\u220fc m\u00b4t\u00b4 chuy\u201dn \u00c6\u00c8ng \u00c6\u00cbi n\u00aeng kh\u220fc. v\u00cci nhau. B - V\u00c0n d\u00d9ng B. C\u220fc m\u00b4t\u00b4 \u00c6\u00afng y\u2122n \u00c6\u00cbi v\u00cci nhau. C. C\u220fc m\u00b4t\u00b4 \u00c6\u00afng y\u2122n \u00c6\u00cbi v\u00cci \u00b4t\u00b4. D. C\u220fc m\u00b4t\u00b4 v\u00b5 \u00b4t\u00b4 c\u00d4ng chuy\u201dn \u00c6\u00c8ng \u00c6\u00cbi v\u00cci m\u2206t \u00c6\u2260\u00cdng. I - Khoanh tr\ufb02n ch\u02dc c\u220fi \u00c6\u00afng tr\u2260\u00ccc 4. Hai th\u00b7i h\u25canh tr\u00d9, m\u00c8t b\u00aang nh\u00b4m, ph\u2260\u00a8ng \u220fn tr\u2202 l\u00cdi m\u00b5 em cho m\u00c8t b\u00aang \u00c6\u00c2ng khi \u00c6\u2260\u00d3c treo v\u00b5o l\u00b5 \u00c6\u00dbng hai \u00c6\u00abu c\u00a9n \u00c6\ufb02n th\u25ca \u00c6\ufb02n c\u00a9n c\u00a9n b\u00aang (H.18.1). Khi nh\u00dbng 1. Hai l\u02d8c \u00c6\u2260\u00d3c g\u2030i l\u00b5 c\u00a9n b\u00aang khi ng\u00c0p c\u2202 hai v\u00b5o n\u2260\u00ccc th\u25ca \u00c6\ufb02n c\u00a9n s\u0153 th\u2019 n\u00b5o ? A. c\u00d4ng ph\u2260\u00a8ng, c\u00d4ng chi\u201cu, c\u00d4ng \u00c6\u00c8 l\u00ccn. A. Nghi\u2122ng v\u201c b\u2122n ph\u2202i. B. c\u00d4ng ph\u2260\u00a8ng, ng\u2260\u00d3c chi\u201cu, B. Nghi\u2122ng v\u201c b\u2122n tr\u220fi. c\u00d4ng \u00c6\u00c8 l\u00ccn. C. V\u2026n c\u00a9n b\u00aang. C. c\u00d4ng ph\u2260\u00a8ng, c\u00d4ng \u00c6\u00c8 l\u00ccn, c\u00d4ng \u00c6\u2206t l\u2122n m\u00c8t v\u00c0t. D. Ch\u2260a \u00c6\u00d2 d\u02dc ki\u00f7n \u00c6\u201d tr\u2202 l\u00cdi. D. c\u00d4ng \u00c6\u2206t l\u2122n m\u00c8t v\u00c0t, c\u00d4ng \u00c6\u00c8 l\u00ccn, ph\u2260\u00a8ng n\u00aam tr\u2122n c\u00d4ng m\u00c8t \u00c6\u2260\u00cdng th\u00bang, chi\u201cu ng\u2260\u00d3c nhau. 2. Xe \u00b4t\u00b4 \u00c6ang chuy\u201dn \u00c6\u00c8ng \u00c6\u00c8t ng\u00c8t H\u25canh 18.1 d\u0131ng l\u03c0i. H\u00b5nh kh\u220fch trong xe b\ufb01 63 A. ng\u2202 ng\u2260\u00cdi v\u201c ph\u203aa sau. B. nghi\u2122ng ng\u2260\u00cdi sang ph\u203aa tr\u220fi. C. nghi\u2122ng ng\u2260\u00cdi sang ph\u203aa ph\u2202i. D. x\u00b4 ng\u2260\u00cdi v\u201c ph\u203aa tr\u2260\u00ccc.","5. \u00df\u201d chuy\u201dn m\u00c8t v\u00c0t n\u2206ng l\u2122n cao, 2. V\u25ca sao khi m\u00ce n\u00e6p chai b\ufb01 v\u2206n ng\u2260\u00cdi ta d\u00d4ng nhi\u201cu c\u220fch. Li\u00f7u c\u201e ch\u2206t, ng\u2260\u00cdi ta ph\u2202i l\u201et tay b\u00aang c\u220fch n\u00b5o cho ta l\u00d3i v\u201c c\u00b4ng ? C\u00a9u v\u2202i hay cao su ? tr\u2202 l\u00cdi n\u00b5o \u00c6\u00dbng ? 3. C\u220fc h\u00b5nh kh\u220fch \u00c6ang ng\u00c2i tr\u2122n xe A. D\u00d4ng r\ufb02ng r\u2030c \u00c6\u00c8ng. \u00b4t\u00b4 b\u00c1ng th\u2020y m\u25canh b\ufb01 nghi\u2122ng ng\u2260\u00cdi sang ph\u203aa tr\u220fi. H\u00b7i l\u00dbc \u00c6\u201e B. D\u00d4ng r\ufb02ng r\u2030c c\u00cb \u00c6\ufb01nh. xe \u00c6ang \u00c6\u2260\u00d3c l\u220fi sang ph\u203aa n\u00b5o ? C. D\u00d4ng m\u2206t ph\u00bang nghi\u2122ng. D. Kh\u00b4ng c\u201e c\u220fch n\u00b5o cho ta l\u00d3i v\u201c c\u00b4ng. 6. M\u00c8t v\u00c0t \u00c6\u2260\u00d3c n\u00e4m l\u2122n cao theo 4. T\u25cam m\u00c8t v\u203a d\u00d9 ch\u00afng t\u00b7 t\u220fc d\u00d9ng ph\u2260\u00a8ng th\u00bang \u00c6\u00afng. Khi n\u00b5o c\u00d2a \u220fp su\u2020t ph\u00d9 thu\u00c8c v\u00b5o \u00c6\u00c8 l\u00ccn v\u00c0t v\u0131a c\u201e th\u2019 n\u00aeng, v\u0131a c\u201e c\u00d2a \u220fp l\u02d8c v\u00b5 di\u00f7n t\u203ach b\ufb01 \u00e4p. \u00c6\u00c8ng n\u00aeng ? 5. Khi v\u00c0t n\u00cai tr\u2122n m\u2206t ch\u2020t l\u00b7ng th\u25ca A. Ch\u00ff khi v\u00c0t \u00c6ang \u00c6i l\u2122n. l\u02d8c \u00c6\u00bby \u00c9c-si-m\u00e4t \u00c6\u2260\u00d3c t\u203anh nh\u2260 th\u2019 n\u00b5o ? B. Ch\u00ff khi v\u00c0t \u00c6ang r\u00a8i xu\u00cbng. C. Ch\u00ff khi v\u00c0t l\u2122n t\u00cci \u00c6i\u201dm cao nh\u2020t. D. C\u2202 khi v\u00c0t \u00c6ang \u00c6i l\u2122n v\u00b5 \u00c6ang r\u00a8i xu\u00cbng. II - Tr\u2202 l\u00cdi c\u00a9u h\u00b7i 6. Trong nh\u02dcng tr\u2260\u00cdng h\u00d3p d\u2260\u00cci \u00c6\u00a9y tr\u2260\u00cdng h\u00d3p n\u00b5o c\u201e c\u00b4ng c\u00a8 h\u2030c ? 1. Ng\u00c2i trong xe \u00b4t\u00b4 \u00c6ang ch\u03c0y, ta a) C\u00c0u b\u00e4 tr\u00c3o c\u00a9y. th\u2020y hai h\u00b5ng c\u00a9y b\u2122n \u00c6\u2260\u00cdng b) Em h\u2030c sinh ng\u00c2i h\u2030c b\u00b5i. chuy\u201dn \u00c6\u00c8ng theo chi\u201cu ng\u2260\u00d3c c) N\u2260\u00ccc \u00e4p l\u2122n th\u00b5nh b\u25canh \u00c6\u02d8ng. l\u03c0i. Gi\u2202i th\u203ach hi\u00f7n t\u2260\u00d3ng n\u00b5y. d) N\u2260\u00ccc ch\u2202y xu\u00cbng t\u0131 \u00c6\u00c0p ch\u00e6n n\u2260\u00ccc. 64","III - B\u00b5i t\u00c0p 1. M\u00c8t ng\u2260\u00cdi \u00c6i xe \u00c6\u03c0p xu\u00cbng m\u00c8t 5. M\u00c8t l\u02d8c s\u2039 c\u02c6 t\u03c0 n\u00a9ng qu\u2202 t\u03c0 kh\u00cbi c\u220fi d\u00cbc d\u00b5i 100m h\u2019t 25s. l\u2260\u00d3ng 125kg l\u2122n cao 70cm trong Xu\u00cbng h\u2019t d\u00cbc, xe l\u00aen ti\u2019p \u00c6o\u03c0n th\u00cdi gian 0,3 gi\u00a9y. Trong tr\u2260\u00cdng \u00c6\u2260\u00cdng d\u00b5i 50m trong 20s r\u00c2i h\u00d3p n\u00b5y l\u02d8c s\u2039 \u00c6\u2211 ho\u03c0t \u00c6\u00c8ng v\u00cci m\u00cci d\u0131ng h\u00ban. T\u203anh v\u00c0n t\u00cbc c\u00b4ng su\u2020t l\u00b5 bao nhi\u2122u ? trung b\u25canh c\u00d2a ng\u2260\u00cdi \u00c6i xe tr\u2122n m\u00c1i \u00c6o\u03c0n \u00c6\u2260\u00cdng v\u00b5 tr\u2122n c\u2202 qu\u2211ng \u00c6\u2260\u00cdng. 2. M\u00c8t ng\u2260\u00cdi c\u201e kh\u00cbi l\u2260\u00d3ng 45kg. Di\u00f7n t\u203ach ti\u2019p x\u00dbc v\u00cci m\u2206t \u00c6\u2020t c\u00d2a m\u00c1i b\u00b5n ch\u00a9n l\u00b5 150cm2. T\u203anh \u220fp su\u2020t ng\u2260\u00cdi \u00c6\u201e t\u220fc d\u00d9ng l\u2122n m\u2206t \u00c6\u2020t khi : a) \u00df\u00afng c\u2202 hai ch\u00a9n. b) Co m\u00c8t ch\u00a9n. 3. M v\u00b5 N l\u00b5 hai v\u00c0t gi\u00cbng h\u00f7t nhau \u00c6\u2260\u00d3c th\u2202 v\u00b5o hai ch\u2020t l\u00b7ng kh\u220fc nhau c\u201e tr\u2030ng l\u2260\u00d3ng ri\u2122ng l\u00b5 d1 v\u00b5 d2 (H.18.2). a) So s\u220fnh l\u02d8c \u00c6\u00bby \u00c9c-si-m\u00e4t t\u220fc d\u00d9ng l\u2122n M v\u00b5 N. b) Tr\u2030ng l\u2260\u00d3ng ri\u2122ng c\u00d2a ch\u2020t l\u00b7ng n\u00b5o l\u00ccn h\u00a8n ? 4. H\u2211y t\u203anh c\u00b4ng m\u00b5 em th\u02d8c hi\u00f7n H\u25canh 18.2 \u00c6\u2260\u00d3c khi \u00c6i \u00c6\u201cu t\u0131 t\u00abng m\u00c8t l\u2122n 65 t\u00abng hai c\u00d2a ng\u00b4i tr\u2260\u00cdng em (em t\u02d8 cho c\u220fc d\u02dc ki\u00f7n c\u00abn thi\u2019t).","C - Tr\ufb02 ch\u00a8i \u00b4 ch\u02dc H\u00b5ng ngang 8. T\u2122n g\u2030i chuy\u201dn \u00c6\u00c8ng c\u00d2a con l\u00e6c \u00c6\u00c2ng h\u00c2. 1. T\u2122n lo\u03c0i v\u00da kh\u203a c\u00ca ho\u03c0t \u00c6\u00c8ng d\u02d8a tr\u2122n hi\u00f7n t\u2260\u00d3ng th\u2019 n\u00aeng chuy\u201dn ho\u220f th\u00b5nh \u00c6\u00c8ng n\u00aeng. 2. \u00df\u2206c \u00c6i\u201dm v\u00c0n t\u00cbc c\u00d2a v\u00c0t khi v\u00c0t 9. T\u2122n g\u2030i hai l\u02d8c c\u00d4ng \u00c6i\u201dm \u00c6\u2206t, ch\ufb01u t\u220fc d\u00d9ng c\u00d2a l\u02d8c c\u00a9n b\u00aang. c\u00d4ng ph\u2260\u00a8ng, ng\u2260\u00d3c chi\u201cu, c\u00d4ng \u00c6\u00c8 l\u00ccn. 3. Hai t\u0131 d\u00d4ng \u00c6\u201d bi\u201du \u00c6\u03c0t t\u203anh ch\u2020t : \u00df\u00c8ng n\u00aeng v\u00b5 th\u2019 n\u00aeng kh\u00b4ng t\u02d8 H\u00b5ng d\u2030c sinh ra ho\u2206c m\u2020t \u00c6i m\u00b5 ch\u00ff chuy\u201dn H\u2211y x\u220fc \u00c6\ufb01nh n\u00c8i dung c\u00d2a t\u0131 \u00ce ho\u220f t\u0131 d\u03c0ng n\u00b5y sang d\u03c0ng kia. h\u00b5ng d\u2030c m\u00b5u xanh (H.18.3). 4. \u00df\u03c0i l\u2260\u00d3ng \u00c6\u2206c tr\u2260ng cho kh\u2202 n\u00aeng sinh c\u00b4ng trong 1 gi\u00a9y. 5. T\u2122n c\u00d2a l\u02d8c do ch\u2020t l\u00b7ng t\u220fc d\u00d9ng l\u2122n v\u00c0t khi nh\u00dbng v\u00b5o trong ch\u2020t l\u00b7ng. 6. Chuy\u201dn \u00c6\u00c8ng v\u00b5 \u00c6\u00afng y\u2122n c\u201e t\u203anh ch\u2020t n\u00b5y. 7. \u00c9p su\u2020t t\u03c0i c\u220fc \u00c6i\u201dm n\u00aam tr\u2122n c\u00d4ng m\u00c8t m\u2206t ph\u00bang n\u00aam ngang c\u00d2a ch\u2020t l\u00b7ng c\u201e t\u203anh ch\u2020t n\u00b5y. H\u25canh 18.3 66","CH\u00b6\u2022NG II NHI\u00e5T h\u2030c C\u220fc ch\u2020t \u00c6\u2260\u00d3c c\u2020u t\u03c0o nh\u2260 th\u2019 n\u00b5o ? Nhi\u00f7t n\u00aeng l\u00b5 g\u25ca ? C\u201e m\u2020y c\u220fch truy\u201cn nhi\u00f7t n\u00aeng ? Nhi\u00f7t l\u2260\u00d3ng l\u00b5 g\u25ca ? X\u220fc \u00c6\ufb01nh nhi\u00f7t l\u2260\u00d3ng nh\u2260 th\u2019 n\u00b5o ? M\u00c8t trong nh\u02dcng \u00c6\ufb01nh lu\u00c0t t\u00cang qu\u220ft c\u00d2a t\u02d8 nhi\u2122n l\u00b5 \u00c6\ufb01nh lu\u00c0t n\u00b5o ? 67","B\u00b5i 19 C\u00c9C CH\u0192T \u00df\u00b6\u00faC C\u0192U T\u00d1O NH\u00b6 TH\u2044 N\u00c4O ? \u00df\u00ca 50cm3 r\u2260\u00d3u v\u00b5o 50cm3 n\u2260\u00ccc ta kh\u00b4ng thu \u00c6\u2260\u00d3c 100cm3 h\u00c1n h\u00d3p r\u2260\u00d3u v\u00b5 n\u2260\u00ccc, m\u00b5 ch\u00ff thu \u00c6\u2260\u00d3c kho\u2202ng 95cm3 ! V\u00c0y kho\u2202ng 5cm3 h\u00c1n h\u00d3p c\ufb02n l\u03c0i \u00c6\u2211 bi\u2019n \u00c6i \u00c6\u00a9u (H.19.1) ? I - C\u220fc ch\u2020t c\u201e \u00c6\u2260\u00d3c c\u2020u t\u03c0o H\u25canh 19.1 t\u0131 c\u220fc h\u03c0t ri\u2122ng bi\u00f7t kh\u00b4ng ? H\u25canh 19.2. K\u203anh hi\u201dn vi hi\u00f7n \u00c6\u03c0i. C\u220fc ch\u2020t nh\u25can c\u201e v\u0152 nh\u2260 li\u201cn m\u00c8t kh\u00cbi, nh\u2260ng c\u201e th\u02d8c ch\u00dbng li\u201cn m\u00c8t kh\u00cbi hay kh\u00b4ng ? C\u220fch \u00c6\u00a9y tr\u2122n hai ngh\u25can n\u00aem, ng\u2260\u00cdi ta \u00c6\u2211 ngh\u2039 r\u00aang v\u00c0t ch\u2020t kh\u00b4ng li\u201cn m\u00c8t kh\u00cbi m\u00b5 \u00c6\u2260\u00d3c c\u2020u t\u03c0o t\u0131 c\u220fc h\u03c0t ri\u2122ng bi\u00f7t r\u2020t nh\u00b7, m\u00e6t th\u2260\u00cdng kh\u00b4ng th\u201d nh\u25can th\u2020y \u00c6\u2260\u00d3c. Tuy nhi\u2122n, ng\u2260\u00cdi ta kh\u00b4ng l\u00b5m c\u220fch n\u00b5o ch\u00afng minh \u00c6\u2260\u00d3c \u02dd ngh\u2039 c\u00d2a m\u25canh l\u00b5 \u00c6\u00dbng. M\u2211i \u00c6\u2019n \u00c6\u00abu th\u2019 k\u00ff XX, con ng\u2260\u00cdi m\u00cci ch\u00afng minh \u00c6\u2260\u00d3c b\u00aang th\u203a nghi\u00f7m s\u02d8 t\u00c2n t\u03c0i c\u00d2a c\u220fc h\u03c0t ri\u2122ng bi\u00f7t c\u2020u t\u03c0o n\u2122n m\u2030i v\u00c0t m\u00b5 ng\u2260\u00cdi ta g\u2030i l\u00b5 nguy\u2122n t\u02c6 v\u00b5 ph\u00a9n t\u02c6. Nguy\u2122n t\u02c6 l\u00b5 h\u03c0t ch\u2020t nh\u00b7 nh\u2020t, c\ufb02n ph\u00a9n t\u02c6 l\u00b5 m\u00c8t nh\u201em c\u220fc nguy\u2122n t\u02c6 k\u2019t h\u00d3p l\u03c0i. V\u25ca nguy\u2122n t\u02c6 v\u00b5 ph\u00a9n t\u02c6 \u00c6\u201cu v\u00b4 c\u00d4ng nh\u00b7 b\u00e4 n\u2122n c\u220fc ch\u2020t nh\u25can c\u201e v\u0152 nh\u2260 li\u201cn m\u00c8t kh\u00cbi. 68","Ng\u00b5y nay, c\u220fc k\u203anh hi\u201dn vi hi\u00f7n \u00c6\u03c0i (H.19.2) \u00c6\u2211 ch\u00d9p \u00c6\u2260\u00d3c \u2202nh c\u00d2a nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 m\u00c8t s\u00cb ch\u2020t v\u00b5 kh\u00b4ng ai c\ufb02n nghi ng\u00cd v\u201c s\u02d8 t\u00c2n t\u03c0i c\u00d2a nh\u02dcng h\u03c0t n\u00b5y (H.19.3). II - Gi\u02dca c\u220fc ph\u00a9n H\u25canh 19.3. \u00c5nh ch\u00d9p c\u220fc nguy\u2122n t\u02c6 silic qua k\u203anh t\u02c6 c\u201e kho\u2202ng hi\u201dn vi hi\u00f7n \u00c6\u03c0i. c\u220fch hay kh\u00b4ng ? 1. Th\u203a nghi\u00f7m m\u00b4 h\u25canh Ch\u00dbng ta t\u25cam c\u220fch gi\u2202i \u00c6\u220fp c\u00a9u h\u00b7i n\u2122u ra \u00ce \u00c6\u00abu b\u00b5i b\u00aang c\u220fch d\u00d4ng m\u00c8t th\u203a nghi\u00f7m t\u2260\u00a8ng t\u02d8 nh\u2260 th\u203a nghi\u00f7m tr\u00c8n r\u2260\u00d3u v\u00cci n\u2260\u00ccc, \u00c6\u2260\u00d3c g\u2030i l\u00b5 th\u203a nghi\u00f7m m\u00b4 h\u25canh. C1 H\u2211y l\u2020y 50cm3 c\u220ft \u00c6\u00ca v\u00b5o 50cm3 ng\u00b4 r\u00c2i l\u00e6c nh\u00e3 xem c\u201e \u00c6\u2260\u00d3c 100cm3 h\u00c1n h\u00d3p ng\u00b4 v\u00b5 c\u220ft kh\u00b4ng ? H\u2211y gi\u2202i th\u203ach t\u03c0i sao ? 2. Gi\u02dca c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 c\u201e kho\u2202ng c\u220fch C2 H\u2211y c\u00cb g\u00e6ng d\u00d4ng c\u220fch gi\u2202i th\u203ach s\u02d8 h\u00d9t th\u201d t\u203ach trong th\u203a nghi\u00f7m tr\u00c8n c\u220ft v\u00b5o ng\u00b4 \u00c6\u201d gi\u2202i th\u203ach s\u02d8 h\u00d9t th\u201d t\u203ach trong th\u203a nghi\u00f7m tr\u00c8n r\u2260\u00d3u v\u00cci n\u2260\u00ccc. Ch\u00ff khi n\u00b5o kh\u00b4ng gi\u2202i th\u203ach \u00c6\u2260\u00d3c m\u00cci \u00c6\u2030c \u00c6o\u03c0n sau \u00c6\u00a9y : Gi\u02dca c\u220fc h\u03c0t ng\u00b4 c\u201e kho\u2202ng c\u220fch n\u2122n khi \u00c6\u00ca c\u220ft v\u00b5o ng\u00b4, c\u220fc h\u03c0t c\u220ft \u00c6\u2211 xen v\u00b5o nh\u02dcng kho\u2202ng c\u220fch n\u00b5y l\u00b5m cho th\u201d t\u203ach c\u00d2a h\u00c1n h\u00d3p nh\u00b7 h\u00a8n t\u00cang th\u201d t\u203ach c\u00d2a ng\u00b4 v\u00b5 c\u220ft. Gi\u02dca c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc c\u00dang nh\u2260 gi\u02dca c\u220fc ph\u00a9n t\u02c6 r\u2260\u00d3u \u00c6\u201cu c\u201e kho\u2202ng c\u220fch. Khi tr\u00c8n r\u2260\u00d3u v\u00cci n\u2260\u00ccc, c\u220fc ph\u00a9n t\u02c6 r\u2260\u00d3u \u00c6\u2211 xen v\u00b5o kho\u2202ng c\u220fch gi\u02dca c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc v\u00b5 ng\u2260\u00d3c l\u03c0i. V\u25ca th\u2019 m\u00b5 th\u201d t\u203ach c\u00d2a h\u00c1n h\u00d3p r\u2260\u00d3u v\u00b5 n\u2260\u00ccc gi\u2202m. C\u220fc \u2202nh ch\u00d9p nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 qua k\u203anh hi\u201dn vi hi\u00f7n \u00c6\u03c0i c\u00dang cho th\u2020y gi\u02dca ch\u00dbng c\u201e kho\u2202ng c\u220fch (H.19.3). 69","III - V\u00c0n d\u00d9ng H\u2211y v\u00c0n d\u00d9ng nh\u02dcng \u00c6i\u201cu \u00c6\u2211 h\u2030c \u00ce tr\u2122n \u00c6\u201d gi\u2202i th\u203ach c\u220fc hi\u00f7n t\u2260\u00d3ng sau \u00c6\u00a9y. C3 Th\u2202 m\u00c8t c\u00d9c \u00c6\u2260\u00cdng v\u00b5o m\u00c8t c\u00cbc n\u2260\u00ccc r\u00c2i khu\u2020y l\u2122n, \u00c6\u2260\u00cdng tan v\u00b5 n\u2260\u00ccc c\u201e v\ufb01 ng\u2030t. C4 Qu\u2202 b\u201eng cao su ho\u2206c qu\u2202 b\u201eng bay b\u00a8m c\u00aeng, d\u00d4 c\u201e bu\u00c8c th\u00c0t ch\u2206t c\u00dang c\u00af ng\u00b5y m\u00c8t x\u00e3p d\u00abn. C5 C\u220f mu\u00cbn s\u00cbng \u00c6\u2260\u00d3c ph\u2202i c\u201e kh\u00b4ng kh\u203a, nh\u2260ng ta th\u2020y c\u220f v\u2026n s\u00cbng \u00c6\u2260\u00d3c trong n\u2260\u00ccc. C\u220fc ch\u2020t \u00c6\u2260\u00d3c c\u2020u t\u03c0o t\u0131 c\u220fc h\u03c0t ri\u2122ng bi\u00f7t g\u2030i l\u00b5 nguy\u2122n t\u02c6, ph\u00a9n t\u02c6. Gi\u02dca c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 c\u201e kho\u2202ng c\u220fch. C\u201e th\u201d em ch\u2260a bi\u2019t Kh\u00cbi l\u2260\u00d3ng c\u00d2a Tr\u220fi \u00df\u2020t l\u00ccn h\u00a8n kh\u00cbi l\u2260\u00d3ng c\u00d2a qu\u2202 cam bao nhi\u2122u l\u00abn th\u25ca kh\u00cbi l\u2260\u00d3ng c\u00d2a qu\u2202 cam l\u00ccn h\u00a8n kh\u00cbi l\u2260\u00d3ng c\u00d2a ph\u00a9n t\u02c6 hi\u00c6r\u00b4 b\u2020y nhi\u2122u l\u00abn. N\u2019u x\u2019p m\u00c8t tr\u00aem tri\u00f7u ph\u00a9n t\u02c6 n\u2260\u00ccc n\u00cbi li\u201cn nhau th\u00b5nh m\u00c8t h\u00b5ng th\u25ca c\u00dang ch\u2260a d\u00b5i \u00c6\u2019n 2cm. N\u2019u t\u2260\u00ceng t\u2260\u00d3ng m\u00c1i v\u00c0t \u00c6\u201cu l\u00ccn l\u2122n g\u2020p m\u00c8t tri\u00f7u l\u00abn, ngh\u2039a l\u00b5 m\u00c8t con mu\u00c1i s\u0153 tr\u00ce th\u00b5nh m\u00c8t con v\u00c0t kh\u00cang l\u00c2 d\u00b5i t\u00cci 10km th\u25ca k\u203ach th\u2260\u00ccc c\u00d2a m\u00c1i ph\u00a9n t\u02c6 v\u2026n ch\u2260a l\u00ccn b\u00aang m\u00c8t d\u2020u ch\u2020m (.). 70","B\u00b5i 20 NGUY\u00a3N T^, PH\u00a2N T^ CHUY\u00d5N \u00df\u00f3NG HAY \u00df`NG Y\u00a3N ? H\u2211y t\u2260\u00ceng t\u2260\u00d3ng gi\u02dca s\u00a9n b\u201eng \u00c6\u220f c\u201e H\u25canh 20.1 m\u00c8t qu\u2202 b\u201eng kh\u00cang l\u00c2 v\u00b5 r\u2020t nhi\u201cu h\u2030c sinh t\u0131 m\u2030i ph\u203aa ch\u03c0y \u00c6\u2019n x\u00b4 \u00c6\u00bby qu\u2202 b\u201eng. V\u25ca nh\u02dcng x\u00b4 \u00c6\u00bby n\u00b5y kh\u00b4ng c\u00a9n b\u00aang n\u2122n qu\u2202 b\u201eng l\u00dbc bay l\u2122n, khi r\u00a8i xu\u00cbng, l\u00dbc b\u00c0t sang tr\u220fi, khi l\u00aen sang ph\u2202i...(H.20.1). Tr\ufb02 ch\u00a8i n\u00b5y t\u2260\u00ceng nh\u2260 ch\u00bang c\u201e li\u2122n quan g\u25ca \u00c6\u2019n nguy\u2122n t\u02c6, ph\u00a9n t\u02c6, th\u2019 m\u00b5 l\u03c0i c\u201e th\u201d gi\u00dbp ch\u00dbng ta hi\u201du m\u00c8t trong nh\u02dcng t\u203anh ch\u2020t quan tr\u2030ng nh\u2020t c\u00d2a nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 s\u0153 h\u2030c trong b\u00b5i n\u00b5y. I - Th\u203a nghi\u00f7m B\u00a8-rao N\u00aem 1827 nh\u00b5 b\u220fc h\u2030c Brao-n\u00a8 (ng\u2260\u00cdi Anh), khi quan s\u220ft c\u220fc h\u03c0t ph\u2020n hoa trong n\u2260\u00ccc b\u00aang k\u203anh hi\u201dn vi \u00c6\u2211 ph\u220ft hi\u00f7n th\u2020y ch\u00dbng chuy\u201dn \u00c6\u00c8ng kh\u00b4ng ng\u0131ng v\u201c m\u2030i ph\u203aa (H.20.2). \u00f4 th\u00cdi k\u25ca \u00c6\u201e, l\u203a thuy\u2019t v\u201c v\u00c0t ch\u2020t \u00c6\u2260\u00d3c c\u2020u t\u03c0o t\u0131 c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 ch\u2260a ra \u00c6\u00cdi n\u2122n \u00b4ng kh\u00b4ng l\u00b5m sao gi\u2202i th\u203ach \u00c6\u2260\u00d3c chuy\u201dn \u00c6\u00c8ng k\u25ca l\u03c0 n\u00b5y. II - c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 chuy\u201dn \u00c6\u00c8ng kh\u00b4ng ng\u0131ng C\u220fc em h\u2211y th\u02c6 gi\u2202i th\u203ach chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc h\u03c0t ph\u2020n hoa trong th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8 b\u00aang c\u220fch d\u00d4ng s\u02d8 t\u2260\u00a8ng t\u02d8 gi\u02dca chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc h\u03c0t ph\u2020n hoa v\u00cci chuy\u201dn \u00c6\u00c8ng c\u00d2a qu\u2202 b\u201eng m\u00b4 t\u2202 \u00ce ph\u00abn m\u00ce b\u00b5i. Sau \u00c6\u00a9y l\u00b5 c\u220fc c\u00a9u h\u00b7i g\u00d3i \u02dd : C1 Qu\u2202 b\u201eng t\u2260\u00a8ng t\u02d8 v\u00cci h\u03c0t n\u00b5o trong th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8 ? C2 C\u220fc h\u2030c sinh t\u2260\u00a8ng t\u02d8 v\u00cci nh\u02dcng h\u03c0t n\u00b5o trong th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8 ? 71","C3 T\u03c0i sao c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc c\u201e th\u201d l\u00b5m cho c\u220fc An-be Anh-xtanh h\u03c0t ph\u2020n hoa chuy\u201dn \u00c6\u00c8ng ? (1879 - 1955) N\u2019u c\u220fc em kh\u00b4ng tr\u2202 l\u00cdi \u00c6\u2260\u00d3c th\u25ca c\u00dang \u00c6\u0131ng bu\u00c2n v\u25ca ph\u2202i h\u00a8n n\u00aem m\u2260\u00a8i n\u00aem sau th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8, c\u220fc nh\u00b5 khoa h\u2030c m\u00cci b\u2260\u00ccc \u00c6\u00abu t\u25cam ra nguy\u2122n nh\u00a9n c\u00d2a chuy\u201dn \u00c6\u00c8ng n\u00b5y, v\u00b5 m\u2211i t\u00cci n\u00aem 1905, nh\u00b5 v\u00c0t l\u203a An-be Anh-xtanh (ng\u2260\u00cdi \u00df\u00afc) m\u00cci gi\u2202i th\u203ach \u00c6\u2260\u00d3c \u00c6\u00aby \u00c6\u00d2 v\u00b5 ch\u203anh x\u220fc th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8. Nguy\u2122n nh\u00a9n g\u00a9y ra chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc h\u03c0t ph\u2020n hoa trong th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8 l\u00b5 do c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc kh\u00b4ng \u00c6\u00afng y\u2122n m\u00b5 chuy\u201dn \u00c6\u00c8ng h\u00c1n \u00c6\u00c8n kh\u00b4ng ng\u0131ng. Trong khi chuy\u201dn \u00c6\u00c8ng c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc va ch\u03c0m v\u00b5o c\u220fc h\u03c0t ph\u2020n hoa t\u0131 nhi\u201cu ph\u203aa (H.20.3), c\u220fc va ch\u03c0m n\u00b5y kh\u00b4ng c\u00a9n b\u00aang nhau l\u00b5m cho c\u220fc h\u03c0t ph\u2020n hoa chuy\u201dn \u00c6\u00c8ng h\u00c1n \u00c6\u00c8n kh\u00b4ng ng\u0131ng. III - chuy\u201dn \u00c6\u00c8ng ph\u00a9n t\u02c6 v\u00b5 nhi\u00f7t \u00c6\u00c8 H\u25canh 20.2. Chuy\u201dn \u00c6\u00c8ng c\u00d2a h\u03c0t ph\u2020n hoa trong Trong th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8 n\u2019u ta c\u00b5ng t\u00aeng th\u203a nghi\u00f7m c\u00d2a Brao-n\u00a8. nhi\u00f7t \u00c6\u00c8 c\u00d2a n\u2260\u00ccc th\u25ca chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc h\u03c0t ph\u2020n hoa c\u00b5ng nhanh, ch\u00afng t\u00b7 c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc H\u25canh 20.3. S\u02d8 va ch\u03c0m chuy\u201dn \u00c6\u00c8ng c\u00b5ng nhanh v\u00b5 va \u00c6\u00c0p v\u00b5o c\u220fc h\u03c0t c\u00d2a c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc v\u00b5o ph\u2020n hoa c\u00b5ng m\u03c0nh. Nhi\u201cu th\u203a nghi\u00f7m kh\u220fc c\u00dang ch\u00afng t\u00b7 : Nhi\u00f7t \u00c6\u00c8 c\u00b5ng cao, c\u220fc nguy\u2122n h\u03c0t ph\u2020n hoa. t\u02c6, ph\u00a9n t\u02c6 chuy\u201dn \u00c6\u00c8ng c\u00b5ng nhanh. V\u25ca chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 li\u2122n quan ch\u2206t ch\u0153 v\u00cci nhi\u00f7t \u00c6\u00c8 n\u2122n chuy\u201dn \u00c6\u00c8ng n\u00b5y \u00c6\u2260\u00d3c g\u2030i l\u00b5 chuy\u201dn \u00c6\u00c8ng nhi\u00f7t. IV - v\u00c0n d\u00d9ng C4 \u00df\u00ca nh\u00e3 n\u2260\u00ccc v\u00b5o m\u00c8t b\u25canh \u00c6\u02d8ng dung d\ufb01ch \u00c6\u00c2ng sunfat m\u00b5u xanh (H.20.4). V\u25ca n\u2260\u00ccc nh\u00e3 h\u00a8n n\u2122n n\u00cai \u00ce tr\u2122n t\u03c0o th\u00b5nh m\u00c8t m\u2206t ph\u00a9n c\u220fch gi\u02dca hai ch\u2020t l\u00b7ng. Sau m\u00c8t th\u00cdi gian, m\u2206t ph\u00a9n c\u220fch n\u00b5y m\u00cd d\u00abn r\u00c2i m\u2020t h\u00ban. Trong b\u25canh ch\u00ff c\ufb02n m\u00c8t ch\u2020t l\u00b7ng \u00c6\u00c2ng nh\u2020t m\u00b5u xanh nh\u03c0t. N\u2260\u00ccc v\u00b5 \u00c6\u00c2ng sunfat \u00c6\u2211 ho\u00b5 l\u2026n v\u00b5o nhau. 72","Hi\u00f7n t\u2260\u00d3ng n\u00b5y g\u2030i l\u00b5 hi\u00f7n t\u2260\u00d3ng khu\u2019ch t\u220fn. H\u2211y d\u00d4ng nh\u02dcng hi\u201du bi\u2019t c\u00d2a m\u25canh v\u201c nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 \u00c6\u201d gi\u2202i th\u203ach hi\u00f7n t\u2260\u00d3ng tr\u2122n. C5 T\u03c0i sao trong n\u2260\u00ccc H\u25canh 20.4 h\u00c2, ao, s\u00b4ng, bi\u201dn l\u03c0i c\u201e kh\u00b4ng kh\u203a m\u2206c d\u00d4 kh\u00b4ng kh\u203a nh\u00e3 h\u00a8n n\u2260\u00ccc r\u2020t nhi\u201cu ? C6 Hi\u00f7n t\u2260\u00d3ng khu\u2019ch t\u220fn c\u201e x\u2202y ra nhanh h\u00a8n khi t\u00aeng nhi\u00f7t \u00c6\u00c8 kh\u00b4ng ? T\u03c0i sao ? C7 B\u00b7 v\u00b5i h\u03c0t thu\u00cbc t\u203am v\u00b5o m\u00c8t c\u00cbc \u00c6\u02d8ng n\u2260\u00ccc l\u03c0nh v\u00b5 m\u00c8t c\u00cbc \u00c6\u02d8ng n\u2260\u00ccc n\u201eng. Quan s\u220ft hi\u00f7n t\u2260\u00d3ng x\u2202y ra v\u00b5 gi\u2202i th\u203ach. C\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 chuy\u201dn \u00c6\u00c8ng kh\u00b4ng ng\u0131ng. Nhi\u00f7t \u00c6\u00c8 c\u00d2a v\u00c0t c\u00b5ng cao th\u25ca c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 c\u2020u t\u03c0o n\u2122n v\u00c0t chuy\u201dn \u00c6\u00c8ng c\u00b5ng nhanh. C\u201e th\u201d em ch\u2260a bi\u2019t \u00f4 nhi\u00f7t \u00c6\u00c8 0oC c\u220fc ph\u00a9n t\u02c6 hi\u00c6r\u00b4 chuy\u201dn \u00c6\u00c8ng v\u00cci v\u00c0n t\u00cbc trung b\u25canh kho\u2202ng 1 700m\/s, ngh\u2039a l\u00b5 kho\u2202ng 6 120km\/h, nhanh g\u2020p h\u00a8n n\u00aem l\u00abn c\u220fc m\u220fy bay ph\u2202n l\u02d8c hi\u00f7n \u00c6\u03c0i. C\u220fc ph\u00a9n t\u02c6 kh\u203a chuy\u201dn \u00c6\u00c8ng trong ph\ufb02ng v\u00cci v\u00c0n t\u00cbc trung b\u25canh t\u0131 100m\/s \u00c6\u2019n 2 000m\/s. T\u03c0i sao khi m\u00ce l\u2030 n\u2260\u00ccc hoa \u00ce \u00c6\u00abu l\u00ccp th\u25ca ph\u2202i v\u00b5i gi\u00a9y sau \u00ce cu\u00cbi l\u00ccp m\u00cci ng\u02c6i th\u2020y m\u00d4i n\u2260\u00ccc hoa ? \u00df\u201e l\u00b5 v\u25ca, c\u220fc ph\u00a9n t\u02c6 n\u2260\u00ccc hoa kh\u00b4ng chuy\u201dn \u00c6\u00c8ng th\u00bang t\u0131 \u00c6\u00abu l\u00ccp \u00c6\u2019n cu\u00cbi l\u00ccp, m\u00b5 chuy\u201dn \u00c6\u00c8ng d\u203ach d\u00e6c t\u0131ng \u00c6o\u03c0n r\u2020t ng\u00e6n do b\ufb01 va ch\u03c0m v\u00b5o c\u220fc ph\u00a9n t\u02c6 kh\u00b4ng kh\u203a, gi\u00cbng nh\u2260 m\u00c8t ng\u2260\u00cdi \u00c6i trong \u00c6\u220fm \u00c6\u00b4ng, h\u2019t ch\u03c0m ph\u2202i ng\u2260\u00cdi n\u00b5y l\u03c0i va ph\u2202i ng\u2260\u00cdi kia. 73","B\u00b5i 21 NHI\u00e5T N\u00b0NG Trong th\u203a nghi\u00f7m v\u201c th\u2202 qu\u2202 b\u201eng r\u00a8i (H.21.1), m\u00c1i l\u00abn qu\u2202 b\u201eng n\u2202y l\u2122n, \u00c6\u00c8 cao c\u00d2a n\u201e l\u03c0i gi\u2202m d\u00abn. Cu\u00cbi c\u00d4ng kh\u00b4ng n\u2202y l\u2122n \u00c6\u2260\u00d3c n\u02dca. Trong hi\u00f7n t\u2260\u00d3ng n\u00b5y r\u201a r\u00b5ng l\u00b5 c\u00a8 n\u00aeng \u00c6\u2211 gi\u2202m d\u00abn. V\u00c0y c\u00a8 n\u00aeng \u00c6\u2211 bi\u2019n m\u2020t hay \u00c6\u2211 chuy\u201dn th\u00b5nh m\u00c8t d\u03c0ng n\u00aeng l\u2260\u00d3ng kh\u220fc ? I - nhi\u00f7t n\u00aeng H\u25canh 21.1 C\u220fc ph\u00a9n t\u02c6 c\u2020u t\u03c0o n\u2122n v\u00c0t chuy\u201dn \u00c6\u00c8ng kh\u00b4ng ng\u0131ng, do \u00c6\u201e ch\u00dbng c\u201e \u00c6\u00c8ng n\u00aeng. T\u00cang \u00c6\u00c8ng n\u00aeng c\u00d2a c\u220fc ph\u00a9n t\u02c6 c\u2020u t\u03c0o n\u2122n v\u00c0t g\u2030i l\u00b5 nhi\u00f7t n\u00aeng c\u00d2a v\u00c0t. Nhi\u00f7t n\u00aeng c\u201e quan h\u00f7 ch\u2206t ch\u0153 v\u00cci nhi\u00f7t \u00c6\u00c8. Nhi\u00f7t \u00c6\u00c8 c\u00d2a v\u00c0t c\u00b5ng cao th\u25ca c\u220fc ph\u00a9n t\u02c6 c\u2020u t\u03c0o n\u2122n v\u00c0t chuy\u201dn \u00c6\u00c8ng c\u00b5ng nhanh v\u00b5 nhi\u00f7t n\u00aeng c\u00d2a v\u00c0t c\u00b5ng l\u00ccn. II - c\u220fc c\u220fch l\u00b5m thay \u00c6\u00cai nhi\u00f7t n\u00aeng C\u220fc em h\u2211y th\u2202o lu\u00c0n xem l\u00b5m th\u2019 n\u00b5o \u00c6\u201d thay \u00c6\u00cai nhi\u00f7t n\u00aeng c\u00d2a m\u00c8t v\u00c0t, v\u203a d\u00d9 l\u00b5m th\u2019 n\u00b5o \u00c6\u201d t\u00aeng nhi\u00f7t n\u00aeng c\u00d2a m\u00c8t mi\u2019ng \u00c6\u00c2ng ? C\u220fc em c\u201e th\u201d t\u25cam ra nhi\u201cu c\u220fch kh\u220fc nhau, nh\u2260ng c\u201e th\u201d quy v\u201c hai c\u220fch sau \u00c6\u00a9y : 1. Th\u02d8c hi\u00f7n c\u00b4ng. Khi ta th\u02d8c hi\u00f7n c\u00b4ng l\u2122n mi\u2019ng \u00c6\u00c2ng, th\u25ca nhi\u00f7t n\u00aeng c\u00d2a mi\u2019ng \u00c6\u00c2ng t\u00aeng v\u00b5 n\u201e n\u201eng l\u2122n. C1 C\u220fc em h\u2211y ngh\u2039 ra m\u00c8t th\u203a nghi\u00f7m \u00c6\u00a8n gi\u2202n \u00c6\u201d ch\u00afng t\u00b7 khi th\u02d8c hi\u00f7n c\u00b4ng l\u2122n mi\u2019ng \u00c6\u00c2ng, mi\u2019ng \u00c6\u00c2ng s\u0153 n\u201eng l\u2122n. 74","2. Truy\u201cn nhi\u00f7t. M\u2206c d\u00d4 kh\u00b4ng th\u02d8c hi\u00f7n c\u00b4ng, nh\u2260ng ta c\u00dang c\u201e th\u201d l\u00b5m cho nhi\u00f7t n\u00aeng c\u00d2a mi\u2019ng \u00c6\u00c2ng t\u00aeng. V\u203a d\u00d9, cho mi\u2019ng \u00c6\u00c2ng ti\u2019p x\u00dbc v\u00cci nh\u02dcng v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 cao h\u00a8n n\u201e, khi \u00c6\u201e mi\u2019ng \u00c6\u00c2ng s\u0153 n\u201eng l\u2122n, nhi\u00f7t n\u00aeng c\u00d2a n\u201e t\u00aeng, c\ufb02n v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 cao h\u00a8n th\u25ca l\u03c0nh \u00c6i, nhi\u00f7t n\u00aeng c\u00d2a n\u201e gi\u2202m. V\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 cao \u00c6\u2211 truy\u201cn cho mi\u2019ng \u00c6\u00c2ng m\u00c8t ph\u00abn nhi\u00f7t n\u00aeng c\u00d2a n\u201e. C\u220fch l\u00b5m thay \u00c6\u00cai nhi\u00f7t n\u00aeng m\u00b5 kh\u00b4ng c\u00abn th\u02d8c hi\u00f7n c\u00b4ng g\u2030i l\u00b5 truy\u201cn nhi\u00f7t. C2 C\u220fc em h\u2211y ngh\u2039 ra m\u00c8t th\u203a nghi\u00f7m \u00c6\u00a8n gi\u2202n \u00c6\u201d minh ho\u03c0 vi\u00f7c l\u00b5m t\u00aeng nhi\u00f7t n\u00aeng c\u00d2a m\u00c8t v\u00c0t b\u00aang c\u220fch truy\u201cn nhi\u00f7t. III - nhi\u00f7t l\u2260\u00d3ng Ph\u00abn nhi\u00f7t n\u00aeng m\u00b5 v\u00c0t nh\u00c0n th\u2122m \u00c6\u2260\u00d3c hay m\u2020t b\u00cct \u00c6i trong qu\u220f tr\u25canh truy\u201cn nhi\u00f7t \u00c6\u2260\u00d3c g\u2030i l\u00b5 nhi\u00f7t l\u2260\u00d3ng. Nhi\u00f7t l\u2260\u00d3ng \u00c6\u2260\u00d3c k\u203a hi\u00f7u b\u00aang ch\u02dc Q. \u00df\u00a8n v\ufb01 c\u00d2a nhi\u00f7t l\u2260\u00d3ng l\u00b5 jun (J). IV - v\u00c0n d\u00d9ng C3 Nung n\u201eng m\u00c8t mi\u2019ng \u00c6\u00c2ng r\u00c2i th\u2202 v\u00b5o m\u00c8t c\u00cbc n\u2260\u00ccc l\u03c0nh. H\u00b7i nhi\u00f7t n\u00aeng c\u00d2a mi\u2019ng \u00c6\u00c2ng v\u00b5 c\u00d2a n\u2260\u00ccc thay \u00c6\u00cai nh\u2260 th\u2019 n\u00b5o ? \u00df\u00a9y l\u00b5 s\u02d8 th\u02d8c hi\u00f7n c\u00b4ng hay truy\u201cn nhi\u00f7t ? C4 Xoa hai b\u00b5n tay v\u00b5o nhau ta th\u2020y tay n\u201eng l\u2122n. Trong hi\u00f7n t\u2260\u00d3ng n\u00b5y \u00c6\u2211 c\u201e s\u02d8 chuy\u201dn ho\u220f n\u00aeng l\u2260\u00d3ng t\u0131 d\u03c0ng n\u00b5o sang d\u03c0ng n\u00b5o ? \u00df\u00a9y l\u00b5 s\u02d8 th\u02d8c hi\u00f7n c\u00b4ng hay truy\u201cn nhi\u00f7t ? C5 H\u2211y d\u00d4ng nh\u02dcng ki\u2019n th\u00afc \u00c6\u2211 h\u2030c trong b\u00b5i \u00c6\u201d gi\u2202i th\u203ach hi\u00f7n t\u2260\u00d3ng n\u2122u ra \u00ce \u00c6\u00abu b\u00b5i. Nhi\u00f7t n\u00aeng c\u00d2a m\u00c8t v\u00c0t l\u00b5 t\u00cang \u00c6\u00c8ng n\u00aeng c\u00d2a c\u220fc ph\u00a9n t\u02c6 c\u2020u t\u03c0o n\u2122n v\u00c0t. Nhi\u00f7t n\u00aeng c\u00d2a m\u00c8t v\u00c0t c\u201e th\u201d thay \u00c6\u00cai b\u00aang hai c\u220fch : Th\u02d8c hi\u00f7n c\u00b4ng ho\u2206c truy\u201cn nhi\u00f7t. Nhi\u00f7t l\u2260\u00d3ng l\u00b5 ph\u00abn nhi\u00f7t n\u00aeng m\u00b5 v\u00c0t nh\u00c0n th\u2122m \u00c6\u2260\u00d3c hay m\u2020t b\u00cct \u00c6i trong qu\u220f tr\u25canh truy\u201cn nhi\u00f7t. \u00df\u00a8n v\ufb01 c\u00d2a nhi\u00f7t n\u00aeng v\u00b5 nhi\u00f7t l\u2260\u00d3ng l\u00b5 jun (J). 75","C\u201e th\u201d em ch\u2260a bi\u2019t Ph\u2202i m\u2020t nhi\u201cu th\u2019 k\u00ff, con ng\u2260\u00cdi m\u00cci tr\u2202 l\u00cdi \u00c6\u2260\u00d3c c\u00a9u h\u00b7i v\u201c b\u2202n ch\u2020t c\u00d2a nhi\u00f7t l\u00b5 g\u25ca ? L\u00b4-m\u00b4-n\u00b4-x\u00cbp V\u00b5o \u00c6\u00abu th\u2019 k\u00ff XVIII, ng\u2260\u00cdi ta cho r\u00aang nhi\u00f7t l\u00b5 (1711 - 1765) m\u00c8t ch\u2020t \u00c6\u2206c bi\u00f7t g\u2030i l\u00b5 \\\"ch\u2020t nhi\u00f7t\\\". \u00df\u201e l\u00b5 m\u00c8t ch\u2020t l\u00b7ng v\u00b4 h\u25canh, kh\u00b4ng c\u201e tr\u2030ng l\u2260\u00d3ng, Jun (1818 - 1889) th\u2020m s\u00a9u v\u00b5o m\u2030i v\u00c0t v\u00b5 c\u201e th\u201d truy\u201cn d\u2018 d\u00b5ng t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc. Thuy\u2019t ch\u2020t nhi\u00f7t c\u201e th\u201d gi\u2202i th\u203ach \u00c6\u2260\u00d3c m\u00c8t s\u00cb hi\u00f7n t\u2260\u00d3ng nhi\u00f7t trong \u00c6\u201e c\u201e s\u02d8 truy\u201cn nhi\u00f7t, nh\u2260ng kh\u00b4ng gi\u2202i th\u203ach \u00c6\u2260\u00d3c nhi\u201cu hi\u00f7n t\u2260\u00d3ng nhi\u00f7t kh\u220fc trong \u00c6\u201e c\u201e hi\u00f7n t\u2260\u00d3ng thay \u00c6\u00cai nhi\u00f7t n\u00aeng b\u00aang c\u220fch th\u02d8c hi\u00f7n c\u00b4ng. \u00df\u00c2ng th\u00cdi v\u00cci thuy\u2019t ch\u2020t nhi\u00f7t c\ufb02n c\u201e thuy\u2019t cho r\u00aang b\u2202n ch\u2020t c\u00d2a nhi\u00f7t l\u00b5 do chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc h\u03c0t v\u00c0t ch\u2020t. Trong s\u00cb nh\u02dcng ng\u2260\u00cdi \u00d2ng h\u00c8 thuy\u2019t n\u00b5y c\u201e c\u220fc nh\u00b5 v\u00c0t l\u203a n\u00cai ti\u2019ng nh\u2260 Niu-t\u00a8n (ng\u2260\u00cdi Anh), Ma-ri-\u00cbt (ng\u2260\u00cdi Ph\u220fp), L\u00b4-m\u00b4-n\u00b4-x\u00cbp (ng\u2260\u00cdi Nga), Jun (ng\u2260\u00cdi Anh). Tuy nhi\u2122n c\u00dang ph\u2202i ch\u00cd \u00c6\u2019n \u00c6\u00abu th\u2019 k\u00ff XIX, khi thuy\u2019t v\u201c v\u00c0t ch\u2020t \u00c6\u2260\u00d3c c\u2020u t\u03c0o t\u0131 c\u220fc nguy\u2122n t\u02c6, ph\u00a9n t\u02c6 ra \u00c6\u00cdi ng\u2260\u00cdi ta m\u00cci c\u00b4ng nh\u00c0n b\u2202n ch\u2020t c\u00d2a nhi\u00f7t l\u00b5 do chuy\u201dn \u00c6\u00c8ng c\u00d2a c\u220fc h\u03c0t v\u00c0t ch\u2020t c\u2020u t\u03c0o n\u2122n v\u00c0t. 76","B\u00b5i 22 D\u221aN NHI\u00e5T Trong s\u02d8 truy\u201cn nhi\u00f7t, nhi\u00f7t n\u00aeng \u00c6\u2260\u00d3c truy\u201cn t\u0131 ph\u00abn n\u00b5y sang ph\u00abn kh\u220fc c\u00d2a m\u00c8t v\u00c0t, t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc. S\u02d8 truy\u201cn nhi\u00f7t n\u00b5y \u00c6\u2260\u00d3c th\u02d8c hi\u00f7n b\u00aang nh\u02dcng c\u220fch n\u00b5o ? I - s\u02d8 d\u2026n nhi\u00f7t H\u25canh 22.1 1. Th\u203a nghi\u00f7m H\u25canh 22.2 77 Trong th\u203a nghi\u00f7m \u00ce h\u25canh 22.1 c\u220fc \u00c6inh a, b, c, d, e \u00c6\u2260\u00d3c g\u00e6n b\u00aang s\u220fp v\u00b5o thanh \u00c6\u00c2ng AB. D\u00d4ng \u00c6\u00c3n c\u00c2n \u00c6un n\u201eng \u00c6\u00abu A c\u00d2a thanh \u00c6\u00c2ng. Quan s\u220ft v\u00b5 m\u00b4 t\u2202 hi\u00f7n t\u2260\u00d3ng x\u2202y ra. 2. Tr\u2202 l\u00cdi c\u00a9u h\u00b7i C1 C\u220fc \u00c6inh r\u00a8i xu\u00cbng ch\u00afng t\u00b7 \u00c6i\u201cu g\u25ca ? C2 C\u220fc \u00c6inh r\u00a8i xu\u00cbng tr\u2260\u00ccc, sau theo th\u00af t\u02d8 n\u00b5o ? C3 H\u2211y d\u02d8a v\u00b5o th\u00af t\u02d8 r\u00a8i xu\u00cbng c\u00d2a c\u220fc \u00c6inh \u00c6\u201d m\u00b4 t\u2202 s\u02d8 truy\u201cn nhi\u00f7t n\u00aeng trong thanh \u00c6\u00c2ng AB. S\u02d8 truy\u201cn nhi\u00f7t n\u00aeng nh\u2260 trong th\u203a nghi\u00f7m tr\u2122n g\u2030i l\u00b5 s\u02d8 d\u2026n nhi\u00f7t. II - t\u203anh d\u2026n nhi\u00f7t c\u00d2a c\u220fc ch\u2020t H\u2211y d\u02d8a v\u00b5o c\u220fc th\u203a nghi\u00f7m sau \u00c6\u00a9y \u00c6\u201d r\u00dbt ra nh\u00c0n x\u00e4t v\u201c t\u203anh d\u2026n nhi\u00f7t c\u00d2a c\u220fc ch\u2020t r\u00e6n, l\u00b7ng, kh\u203a. Th\u203a nghi\u00f7m 1. D\u00d4ng \u00c6\u00c3n c\u00c2n \u00c6un n\u201eng \u00c6\u00c2ng th\u00cdi c\u220fc thanh \u00c6\u00c2ng, nh\u00b4m, thu\u02da tinh c\u201e \u00c6inh g\u00e6n b\u00aang s\u220fp \u00ce \u00c6\u00abu (H.22.2).","C4 C\u220fc \u00c6inh g\u00e6n \u00ce \u00c6\u00abu c\u220fc thanh c\u201e r\u00a8i H\u25canh 22.3 xu\u00cbng \u00c6\u00c2ng th\u00cdi kh\u00b4ng ? Hi\u00f7n t\u2260\u00d3ng n\u00b5y H\u25canh 22.4 ch\u00afng t\u00b7 \u00c6i\u201cu g\u25ca ? C5 H\u2211y d\u02d8a v\u00b5o th\u203a nghi\u00f7m tr\u2122n \u00c6\u201d so s\u220fnh t\u203anh d\u2026n nhi\u00f7t c\u00d2a \u00c6\u00c2ng, nh\u00b4m, thu\u02da tinh. Ch\u2020t n\u00b5o d\u2026n nhi\u00f7t t\u00cbt nh\u2020t, ch\u2020t n\u00b5o d\u2026n nhi\u00f7t k\u00e4m nh\u2020t ? T\u0131 \u00c6\u201e c\u201e th\u201d r\u00dbt ra k\u2019t lu\u00c0n g\u25ca ? Th\u203a nghi\u00f7m 2. D\u00d4ng \u00c6\u00c3n c\u00c2n \u00c6un n\u201eng mi\u00f7ng m\u00c8t \u00cbng nghi\u00f7m trong c\u201e \u00c6\u02d8ng n\u2260\u00ccc, d\u2260\u00cci \u00c6\u220fy c\u201e m\u00c8t c\u00d9c s\u220fp (H.22.3). C6 Khi n\u2260\u00ccc \u00ce ph\u00abn tr\u2122n c\u00d2a \u00cbng nghi\u00f7m b\u00e6t \u00c6\u00abu s\u00b4i th\u25ca c\u00d9c s\u220fp \u00ce \u00c6\u220fy \u00cbng nghi\u00f7m c\u201e b\ufb01 n\u201eng ch\u2202y kh\u00b4ng ? T\u0131 th\u203a nghi\u00f7m n\u00b5y c\u201e th\u201d r\u00dbt ra nh\u00c0n x\u00e4t g\u25ca v\u201c t\u203anh d\u2026n nhi\u00f7t c\u00d2a ch\u2020t l\u00b7ng ? Th\u203a nghi\u00f7m 3. D\u00d4ng \u00c6\u00c3n c\u00c2n \u00c6un n\u201eng \u00c6\u220fy m\u00c8t \u00cbng nghi\u00f7m trong c\u201e kh\u00b4ng kh\u203a, \u00ce n\u00dbt c\u201e g\u00e6n m\u00c8t c\u00d9c s\u220fp (H.22.4). C7 Khi \u00c6\u220fy \u00cbng nghi\u00f7m \u00c6\u2211 n\u201eng th\u25ca mi\u2019ng s\u220fp g\u00e6n \u00ce n\u00dbt \u00cbng nghi\u00f7m c\u201e b\ufb01 n\u201eng ch\u2202y kh\u00b4ng ? T\u0131 th\u203a nghi\u00f7m n\u00b5y c\u201e th\u201d r\u00dbt ra nh\u00c0n x\u00e4t g\u25ca v\u201c t\u203anh d\u2026n nhi\u00f7t c\u00d2a ch\u2020t kh\u203a ? III - v\u00c0n d\u00d9ng C8 T\u25cam ba v\u203a d\u00d9 v\u201c hi\u00f7n t\u2260\u00d3ng d\u2026n nhi\u00f7t. C9 T\u03c0i sao n\u00c2i, xoong th\u2260\u00cdng l\u00b5m b\u00aang kim lo\u03c0i, c\ufb02n b\u220ft \u00c6\u2039a th\u2260\u00cdng l\u00b5m b\u00aang s\u00af ? C10 T\u03c0i sao v\u201c m\u00d4a \u00c6\u00b4ng m\u2206c nhi\u201cu \u220fo m\u00b7ng \u2020m h\u00a8n m\u2206c m\u00c8t \u220fo d\u00b5y ? C11 V\u201c m\u00d4a n\u00b5o chim th\u2260\u00cdng hay \u00c6\u00afng x\u00d4 l\u00b4ng ? T\u03c0i sao ? C12 T\u03c0i sao trong nh\u02dcng ng\u00b5y r\u00e4t s\u00cd v\u00b5o kim lo\u03c0i ta th\u2020y l\u03c0nh, c\ufb02n trong nh\u02dcng ng\u00b5y n\u00e6ng n\u201eng s\u00cd v\u00b5o kim lo\u03c0i ta l\u03c0i th\u2020y n\u201eng ? 78","Nhi\u00f7t n\u00aeng c\u201e th\u201d truy\u201cn t\u0131 ph\u00abn n\u00b5y sang ph\u00abn kh\u220fc c\u00d2a m\u00c8t v\u00c0t, t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc b\u00aang h\u25canh th\u00afc d\u2026n nhi\u00f7t. Ch\u2020t r\u00e6n d\u2026n nhi\u00f7t t\u00cbt. Trong ch\u2020t r\u00e6n, kim lo\u03c0i d\u2026n nhi\u00f7t t\u00cbt nh\u2020t. Ch\u2020t l\u00b7ng v\u00b5 ch\u2020t kh\u203a d\u2026n nhi\u00f7t k\u00e4m. C\u201e th\u201d em ch\u2260a bi\u2019t B\u2202n ch\u2020t c\u00d2a s\u02d8 d\u2026n nhi\u00f7t l\u00b5 s\u02d8 truy\u201cn \u00c6\u00c8ng n\u00aeng c\u00d2a c\u220fc h\u03c0t v\u00c0t ch\u2020t khi ch\u00dbng va ch\u03c0m v\u00b5o nhau. H\u2211y th\u02c6 d\u00d4ng ki\u2019n th\u00afc tr\u2122n \u00c6\u201d gi\u2202i th\u203ach s\u02d8 d\u2026n nhi\u00f7t trong th\u203a nghi\u00f7m \u00ce h\u25canh 22.1. N\u2019u coi kh\u2202 n\u00aeng d\u2026n nhi\u00f7t c\u00d2a kh\u00b4ng kh\u203a l\u00b5 1 th\u25ca kh\u2202 n\u00aeng d\u2026n nhi\u00f7t c\u00d2a m\u00c8t s\u00cb ch\u2020t c\u201e gi\u220f tr\ufb01 nh\u2260 b\u2202ng 22.1. B\u2202ng 22.1 Ch\u2020t Kh\u2202 n\u00aeng d\u2026n nhi\u00f7t Ch\u2020t Kh\u2202 n\u00aeng d\u2026n nhi\u00f7t Len 2 N\u2260\u00ccc \u00c6\u220f 88 G\u00c1 7 Th\u00e4p 2 860 N\u2260\u00ccc 25 Nh\u00b4m 8 770 Thu\u02da tinh 44 \u00df\u00c2ng 17 370 \u00df\u2020t 65 B\u03c0c 17 720 N\u2019u c\u201e ai n\u201ei l\u00b5 t\u201ec \u00c6\u00cbt kh\u00b4ng ch\u220fy, th\u25ca ch\u00e6c c\u220fc em kh\u00b4ng tin. Nh\u2260ng c\u220fc em th\u02c6 l\u00b5m th\u203a nghi\u00f7m sau. L\u2020y m\u00c8t s\u00d3i t\u201ec cu\u00cbn ch\u2206t quanh m\u00c8t que s\u00e6t d\u00b5i r\u00c2i d\u00d4ng di\u2122m \u00c6\u00cbt, t\u201ec kh\u00b4ng ch\u220fy, ch\u00ff c\u201e que s\u00e6t n\u201eng l\u2122n th\u00b4i. N\u2019u cu\u00cbn t\u201ec quanh m\u00c8t thanh thu\u02da tinh ho\u2206c g\u00c1 th\u25ca khi \u00c6\u00cbt, t\u201ec s\u0153 ch\u220fy ngay. H\u2211y gi\u2202i th\u203ach t\u03c0i sao ? 79","B\u00b5i 23 H\u25canh 23.1 H\u25canh 23.2 \u00df\u02c7I L\u00b6U - B`C X\u00d1 NHI\u00e5T I - \u00c6\u00cbi l\u2260u Trong th\u203a nghi\u00f7m v\u201c s\u02d8 d\u2026n nhi\u00f7t c\u00d2a n\u2260\u00ccc, n\u2019u ta kh\u00b4ng g\u00e6n mi\u2019ng s\u220fp \u00ce \u00c6\u220fy \u00cbng nghi\u00f7m m\u00b5 \u00c6\u201d mi\u2019ng s\u220fp \u00ce mi\u00f7ng \u00cbng nghi\u00f7m v\u00b5 \u00c6un n\u201eng \u00c6\u220fy \u00cbng nghi\u00f7m (H.23.1), th\u25ca ch\u00ff trong m\u00c8t th\u00cdi gian ng\u00e6n s\u220fp \u00c6\u2211 n\u201eng ch\u2202y. Trong tr\u2260\u00cdng h\u00d3p n\u00b5y n\u2260\u00ccc \u00c6\u2211 truy\u201cn nhi\u00f7t b\u00aang c\u220fch n\u00b5o ? 1. Th\u203a nghi\u00f7m \u00df\u2206t m\u00c8t g\u201ei nh\u00b7 \u00c6\u02d8ng c\u220fc h\u03c0t thu\u00cbc t\u203am v\u00b5o \u00c6\u220fy c\u00d2a m\u00c8t c\u00cbc thu\u02da tinh \u00c6\u02d8ng n\u2260\u00ccc r\u00c2i d\u00d4ng \u00c6\u00c3n c\u00c2n \u00c6un n\u201eng c\u00cbc n\u2260\u00ccc \u00ce ph\u203aa c\u201e \u00c6\u2206t thu\u00cbc t\u203am (H.23.2). Quan s\u220ft hi\u00f7n t\u2260\u00d3ng x\u2202y ra. 2. Tr\u2202 l\u00cdi c\u00a9u h\u00b7i C1 N\u2260\u00ccc m\u00b5u t\u203am di chuy\u201dn th\u00b5nh d\ufb02ng t\u0131 d\u2260\u00cci l\u2122n r\u00c2i t\u0131 tr\u2122n xu\u00cbng hay di chuy\u201dn h\u00c1n \u00c6\u00c8n theo m\u2030i ph\u2260\u00a8ng ? C2 T\u03c0i sao l\u00ccp n\u2260\u00ccc \u00ce d\u2260\u00cci \u00c6\u2260\u00d3c \u00c6un n\u201eng l\u03c0i \u00c6i l\u2122n ph\u203aa tr\u2122n, c\ufb02n l\u00ccp n\u2260\u00ccc l\u03c0nh \u00ce ph\u203aa tr\u2122n l\u03c0i \u00c6i xu\u00cbng d\u2260\u00cci ? (H\u2211y nh\u00cc l\u03c0i \u00c6i\u201cu ki\u00f7n \u00c6\u201d v\u00c0t n\u00cai l\u2122n, ch\u25cam xu\u00cbng \u00c6\u2211 h\u2030c trong ph\u00abn C\u00a8 h\u2030c). C3 T\u03c0i sao bi\u2019t \u00c6\u2260\u00d3c n\u2260\u00ccc trong c\u00cbc \u00c6\u2211 n\u201eng l\u2122n ? S\u02d8 truy\u201cn nhi\u00f7t n\u00aeng nh\u00cd t\u03c0o th\u00b5nh c\u220fc d\ufb02ng nh\u2260 trong th\u203a nghi\u00f7m tr\u2122n g\u2030i l\u00b5 s\u02d8 \u00c6\u00cbi l\u2260u. S\u02d8 \u00c6\u00cbi l\u2260u c\u00dang x\u2202y ra trong ch\u2020t kh\u203a. 80","3. V\u00c0n d\u00d9ng H\u25canh 23.3 C4 Trong th\u203a nghi\u00f7m \u00ce h\u25canh 23.3, khi \u00c6\u00cbt n\u2019n AB v\u00b5 h\u2260\u00a8ng ta th\u2020y d\ufb02ng kh\u201ei h\u2260\u00a8ng \u00c6i t\u0131 tr\u2122n xu\u00cbng v\ufb02ng qua khe h\u00ce gi\u02dca mi\u2019ng b\u25caa ng\u00aen v\u00b5 H\u25canh 23.4 \u00c6\u220fy c\u00cbc r\u00c2i \u00c6i l\u2122n ph\u203aa ng\u2030n n\u2019n. H\u2211y gi\u2202i th\u203ach hi\u00f7n t\u2260\u00d3ng tr\u2122n. AB C5 T\u03c0i sao mu\u00cbn \u00c6un n\u201eng ch\u2020t l\u00b7ng v\u00b5 ch\u2020t H\u25canh 23.5 kh\u203a ph\u2202i \u00c6un t\u0131 ph\u203aa d\u2260\u00cci ? 81 C6 Trong ch\u00a9n kh\u00b4ng v\u00b5 trong ch\u2020t r\u00e6n c\u201e x\u2202y ra \u00c6\u00cbi l\u2260u kh\u00b4ng ? T\u03c0i sao ? II - b\u00afc x\u03c0 nhi\u00f7t Ngo\u00b5i l\u00ccp kh\u203a quy\u201dn bao quanh Tr\u220fi \u00df\u2020t, kho\u2202ng kh\u00b4ng gian c\ufb02n l\u03c0i gi\u02dca Tr\u220fi \u00df\u2020t v\u00b5 M\u2206t Tr\u00cdi l\u00b5 kho\u2202ng ch\u00a9n kh\u00b4ng. Trong kho\u2202ng ch\u00a9n kh\u00b4ng n\u00b5y kh\u00b4ng c\u201e s\u02d8 d\u2026n nhi\u00f7t v\u00b5 \u00c6\u00cbi l\u2260u. V\u00c0y n\u00aeng l\u2260\u00d3ng c\u00d2a M\u2206t Tr\u00cdi \u00c6\u2211 truy\u201cn xu\u00cbng Tr\u220fi \u00df\u2020t b\u00aang c\u220fch n\u00b5o ? 1. Th\u203a nghi\u00f7m - M\u00c8t b\u25canh c\u00abu \u00c6\u2211 ph\u00d2 mu\u00c8i \u00c6\u00c3n, tr\u2122n n\u00dbt c\u201e g\u00e6n m\u00c8t \u00cbng thu\u02da tinh, trong \u00cbng thu\u02da tinh c\u201e gi\u2030t n\u2260\u00ccc m\u00b5u. B\u25canh \u00c6\u2260\u00d3c \u00c6\u2206t g\u00abn m\u00c8t ngu\u00c2n nhi\u00f7t nh\u2260 ng\u2030n l\u02c6a \u00c6\u00c3n c\u00c2n (H.23.4). Quan s\u220ft v\u00b5 m\u00b4 t\u2202 hi\u00f7n t\u2260\u00d3ng x\u2202y ra v\u00cci gi\u2030t n\u2260\u00ccc m\u00b5u. - L\u2020y mi\u2019ng g\u00c1 ch\u00e6n gi\u02dca ngu\u00c2n nhi\u00f7t v\u00b5 b\u25canh c\u00abu (H.23.5). Quan s\u220ft v\u00b5 m\u00b4 t\u2202 hi\u00f7n t\u2260\u00d3ng x\u2202y ra v\u00cci gi\u2030t n\u2260\u00ccc m\u00b5u. 2. Tr\u2202 l\u00cdi c\u00a9u h\u00b7i C7 Gi\u2030t n\u2260\u00ccc m\u00b5u d\ufb01ch chuy\u201dn v\u201c \u00c6\u00abu B ch\u00afng t\u00b7 \u00c6i\u201cu g\u25ca ? C8 Gi\u2030t n\u2260\u00ccc m\u00b5u d\ufb01ch chuy\u201dn tr\u00ce l\u03c0i \u00c6\u00abu A ch\u00afng t\u00b7 \u00c6i\u201cu g\u25ca ? Mi\u2019ng g\u00c1 \u00c6\u2211 c\u201e t\u220fc d\u00d9ng g\u25ca ?","C9 S\u02d8 truy\u201cn nhi\u00f7t t\u0131 ngu\u00c2n nhi\u00f7t t\u00cci b\u25canh c\u201e ph\u2202i l\u00b5 d\u2026n nhi\u00f7t v\u00b5 \u00c6\u00cbi l\u2260u kh\u00b4ng ? T\u03c0i sao ? Trong th\u203a nghi\u00f7m tr\u2122n, nhi\u00f7t \u00c6\u2211 \u00c6\u2260\u00d3c truy\u201cn b\u00aang c\u220fc tia nhi\u00f7t \u00c6i th\u00bang. H\u25canh th\u00afc truy\u201cn nhi\u00f7t n\u00b5y g\u2030i l\u00b5 b\u00afc x\u03c0 nhi\u00f7t. B\u00afc x\u03c0 nhi\u00f7t c\u201e th\u201d x\u2202y ra ngay c\u2202 trong ch\u00a9n kh\u00b4ng. Th\u203a nghi\u00f7m cho th\u2020y kh\u2202 n\u00aeng h\u2020p th\u00d9 tia nhi\u00f7t c\u00d2a m\u00c8t v\u00c0t ph\u00d9 thu\u00c8c v\u00b5o t\u203anh ch\u2020t c\u00d2a b\u201c m\u2206t. V\u00c0t c\u201e b\u201c m\u2206t c\u00b5ng x\u00d4 x\u25ca v\u00b5 m\u00b5u c\u00b5ng s\u2026m th\u25ca h\u2020p th\u00d9 tia nhi\u00f7t c\u00b5ng nhi\u201cu. III - V\u00c0n d\u00d9ng C11 T\u03c0i sao v\u201c m\u00d4a h\u00c3 ta th\u2260\u00cdng m\u2206c \u220fo m\u00b5u tr\u00e6ng m\u00b5 kh\u00b4ng m\u2206c \u220fo m\u00b5u \u00c6en ? C10 T\u03c0i sao trong th\u203a nghi\u00f7m \u00ce h\u25canh 23.4 b\u25canh ch\u00afa kh\u00b4ng C12 H\u2211y ch\u2030n t\u0131 th\u203ach h\u00d3p cho c\u220fc \u00b4 tr\u00cbng \u00ce kh\u203a l\u03c0i \u00c6\u2260\u00d3c ph\u00d2 mu\u00c8i \u00c6\u00c3n ? b\u2202ng 23.1. B\u2202ng 23.1 Ch\u2020t R\u00e6n L\u00b7ng Kh\u203a Ch\u00a9n kh\u00b4ng ... ... ... ... H\u25canh th\u00afc truy\u201cn nhi\u00f7t ch\u00d2 y\u2019u \u00df\u00cbi l\u2260u l\u00b5 s\u02d8 truy\u201cn nhi\u00f7t b\u00aang c\u220fc d\ufb02ng ch\u2020t l\u00b7ng ho\u2206c ch\u2020t kh\u203a, \u00c6\u201e l\u00b5 h\u25canh th\u00afc truy\u201cn nhi\u00f7t ch\u00d2 y\u2019u c\u00d2a ch\u2020t l\u00b7ng v\u00b5 ch\u2020t kh\u203a. B\u00afc x\u03c0 nhi\u00f7t l\u00b5 s\u02d8 truy\u201cn nhi\u00f7t b\u00aang c\u220fc tia nhi\u00f7t \u00c6i th\u00bang. B\u00afc x\u03c0 nhi\u00f7t c\u201e th\u201d x\u2202y ra c\u2202 \u00ce trong ch\u00a9n kh\u00b4ng. C\u201e th\u201d em ch\u2260a bi\u2019t H\u25canh 23.6 Ph\u203ach (b\u25canh thu\u02da) l\u00b5 m\u00c8t b\u25canh thu\u02da tinh hai l\u00ccp. Gi\u02dca hai l\u00ccp thu\u02da tinh n\u00b5y l\u00b5 ch\u00a9n kh\u00b4ng \u00c6\u201d ng\u00aen c\u2202n s\u02d8 d\u2026n nhi\u00f7t. Hai m\u2206t \u00c6\u00cbi di\u00f7n c\u00d2a hai l\u00ccp thu\u02da tinh \u00c6\u2260\u00d3c tr\u220fng b\u03c0c \u00c6\u201d ph\u2202n x\u03c0 c\u220fc tia nhi\u00f7t tr\u00ce l\u03c0i n\u2260\u00ccc \u00c6\u02d8ng trong ph\u203ach. Ph\u203ach \u00c6\u2260\u00d3c \u00c6\u00c0y n\u00dbt th\u00c0t k\u203an \u00c6\u201d ng\u00aen c\u2202n s\u02d8 truy\u201cn nhi\u00f7t b\u00aang \u00c6\u00cbi l\u2260u ra b\u2122n ngo\u00b5i. Nh\u00cd \u00c6\u201e m\u00b5 ph\u203ach gi\u02dc \u00c6\u2260\u00d3c n\u2260\u00ccc n\u201eng l\u00a9u d\u00b5i (H.23.6). \u00df\u00c3n k\u00e4o qu\u00a9n quay \u00c6\u2260\u00d3c l\u00b5 nh\u00cd d\ufb02ng \u00c6\u00cbi l\u2260u c\u00d2a kh\u00b4ng kh\u203a. 82","B\u00b5i 24 C\u00a7NG TH`C T\u00eaNH NHI\u00e5T L\u00b6\u00faNG Kh\u00b4ng c\u201e d\u00d9ng c\u00d9 n\u00b5o \u00c6o tr\u02d8c ti\u2019p \u00c6\u2260\u00d3c c\u00b4ng. \u00df\u201d x\u220fc \u00c6\ufb01nh c\u00b4ng c\u00d2a m\u00c8t l\u02d8c, ng\u2260\u00cdi ta ph\u2202i d\u00d4ng l\u02d8c k\u2019 \u00c6o \u00c6\u00c8 l\u00ccn c\u00d2a l\u02d8c v\u00b5 d\u00d4ng th\u2260\u00ccc \u00c6o qu\u2211ng \u00c6\u2260\u00cdng d\ufb01ch chuy\u201dn, t\u0131 \u00c6\u201e t\u203anh c\u00b4ng. T\u2260\u00a8ng t\u02d8 nh\u2260 th\u2019, kh\u00b4ng c\u201e d\u00d9ng c\u00d9 n\u00b5o c\u201e th\u201d \u00c6o tr\u02d8c ti\u2019p nhi\u00f7t l\u2260\u00d3ng. V\u00c0y, mu\u00cbn x\u220fc \u00c6\ufb01nh nhi\u00f7t l\u2260\u00d3ng ng\u2260\u00cdi ta ph\u2202i l\u00b5m th\u2019 n\u00b5o ? I - nhi\u00f7t l\u2260\u00d3ng m\u00c8t v\u00c0t thu v\u00b5o \u00df\u00d5 N\u00efNG L\u00a3N ph\u00d9 thu\u00c8c nh\u02dcng y\u2019u t\u00cb n\u00b5o ? Nhi\u00f7t l\u2260\u00d3ng m\u00c8t v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d l\u00b5m v\u00c0t a) n\u201eng l\u2122n ph\u00d9 thu\u00c8c ba y\u2019u t\u00cb sau \u00c6\u00a9y : b) - Kh\u00cbi l\u2260\u00d3ng c\u00d2a v\u00c0t, - \u00df\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8 c\u00d2a v\u00c0t, - Ch\u2020t c\u2020u t\u03c0o n\u2122n v\u00c0t. \u00df\u201d ki\u201dm tra xem nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n c\u201e ph\u00d9 thu\u00c8c ba y\u2019u t\u00cb tr\u2122n kh\u00b4ng, ng\u2260\u00cdi ta ph\u2202i l\u00b5m th\u2019 n\u00b5o ? (\u00df\u201d tr\u2202 l\u00cdi c\u00a9u h\u00b7i n\u00b5y h\u2211y nh\u00cc l\u03c0i nh\u02dcng tr\u2260\u00cdng h\u00d3p t\u2260\u00a8ng t\u02d8 \u00c6\u2211 h\u2030c \u00ce c\u220fc l\u00ccp d\u2260\u00cci). 1. Quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00b5 kh\u00cbi l\u2260\u00d3ng c\u00d2a v\u00c0t \u00df\u201d ki\u201dm tra m\u00cbi quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t H\u25canh 24.1 c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00b5 kh\u00cbi l\u2260\u00d3ng c\u00d2a v\u00c0t, 83 ng\u2260\u00cdi ta l\u00b5m th\u203a nghi\u00f7m v\u0153 \u00ce h\u25canh 24.1. D\u00d4ng \u00c6\u00c3n c\u00c2n l\u00abn l\u2260\u00d3t \u00c6un hai kh\u00cbi l\u2260\u00d3ng n\u2260\u00ccc kh\u220fc nhau, 50g v\u00b5 100g, \u00c6\u02d8ng trong hai c\u00cbc thu\u02da tinh gi\u00cbng nhau, \u00c6\u201d n\u2260\u00ccc \u00ce trong c\u220fc c\u00cbc \u00c6\u201cu n\u201eng l\u2122n th\u2122m 20oC. K\u2019t qu\u2202 th\u203a nghi\u00f7m \u00c6\u2260\u00d3c ghi \u00ce b\u2202ng 24.1.","B\u2202ng 24.1 Ch\u2020t Kh\u00cbi \u00df\u00c8 t\u00aeng Th\u00cdi gian So s\u220fnh So s\u220fnh l\u2260\u00d3ng nhi\u00f7t \u00c6\u00c8 \u00c6un kh\u00cbi l\u2260\u00d3ng nhi\u00f7t l\u2260\u00d3ng N\u2260\u00ccc C\u00cbc 1 N\u2260\u00ccc 50g \uf044to1=20oC t1=5 ph\u00dbt m1 = m2 Q1= Q2 C\u00cbc 2 \uf044to2=20oC t2=10 ph\u00dbt 100g C1 Trong th\u203a nghi\u00f7m tr\u2122n, y\u2019u t\u00cb n\u00b5o \u00ce hai c\u00cbc \u00c6\u2260\u00d3c gi\u02dc gi\u00cbng nhau, y\u2019u t\u00cb n\u00b5o \u00c6\u2260\u00d3c thay \u00c6\u00cai ? T\u03c0i sao ph\u2202i l\u00b5m nh\u2260 th\u2019 ? H\u2211y t\u25cam s\u00cb th\u203ach h\u00d3p cho c\u220fc \u00b4 tr\u00cbng \u00ce hai c\u00c8t cu\u00cbi b\u2202ng 24.1. Bi\u2019t nhi\u00f7t l\u2260\u00d3ng ng\u2030n l\u02c6a \u00c6\u00c3n c\u00c2n truy\u201cn cho n\u2260\u00ccc t\u00ff l\u00f7 v\u00cci th\u00cdi gian \u00c6un. C2 T\u0131 th\u203a nghi\u00f7m tr\u2122n c\u201e th\u201d k\u2019t lu\u00c0n g\u25ca v\u201c a) m\u00cbi quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00b5 kh\u00cbi l\u2260\u00d3ng c\u00d2a v\u00c0t ? 2. Quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d b) n\u201eng l\u2122n v\u00b5 \u00c6\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8 H\u25canh 24.2 C\u220fc em h\u2211y th\u2202o lu\u00c0n trong nh\u201em v\u201c c\u220fch l\u00b5m th\u203a nghi\u00f7m \u00c6\u201d ki\u201dm tra m\u00cbi quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00b5 \u00c6\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8. Trong khi th\u2202o lu\u00c0n c\u00abn l\u2260u \u02dd nh\u02dcng v\u2020n \u00c6\u201c sau \u00c6\u00a9y : C3 Trong th\u203a nghi\u00f7m n\u00b5y ph\u2202i gi\u02dc kh\u00b4ng \u00c6\u00cai nh\u02dcng y\u2019u t\u00cb n\u00b5o ? Mu\u00cbn v\u00c0y ph\u2202i l\u00b5m th\u2019 n\u00b5o ? C4 Trong th\u203a nghi\u00f7m n\u00b5y ph\u2202i thay \u00c6\u00cai y\u2019u t\u00cb n\u00b5o ? Mu\u00cbn v\u00c0y ph\u2202i l\u00b5m th\u2019 n\u00b5o ? Sau \u00c6\u00a9y l\u00b5 b\u2202ng k\u2019t qu\u2202 th\u203a nghi\u00f7m l\u00b5m v\u00cci hai c\u00cbc, m\u00c1i c\u00cbc \u00c6\u02d8ng 50g n\u2260\u00ccc, \u00c6\u2260\u00d3c l\u00abn l\u2260\u00d3t \u00c6un n\u201eng b\u00aang \u00c6\u00c3n c\u00c2n trong 5 ph\u00dbt, 10 ph\u00dbt (H.24.2). H\u2211y t\u25cam s\u00cb th\u203ach h\u00d3p cho c\u220fc \u00b4 tr\u00cbng \u00ce hai c\u00c8t cu\u00cbi b\u2202ng 24.2. 84","B\u2202ng 24.2 Kh\u00cbi \u00df\u00c8 t\u00aeng Th\u00cdi gian So s\u220fnh So s\u220fnh Ch\u2020t l\u2260\u00d3ng nhi\u00f7t \u00c6\u00c8 \u00c6un \u00c6\u00c8 t\u00aeng nhi\u00f7t l\u2260\u00d3ng nhi\u00f7t \u00c6\u00c8 C\u00cbc 1 N\u2260\u00ccc 50g C\u00cbc 2 N\u2260\u00ccc \uf044to1=20oC t1=5 ph\u00dbt \uf044to1= \uf044to2 Q1 = Q2 50g \uf044to2=40oC t2=10 ph\u00dbt C5 T\u0131 th\u203a nghi\u00f7m tr\u2122n c\u201e th\u201d r\u00dbt ra k\u2019t a) lu\u00c0n g\u25ca v\u201c m\u00cbi quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00b5 \u00c6\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8 ? 3. Quan h\u00f7 gi\u02dca nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu b) v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00cci ch\u2020t l\u00b5m v\u00c0t H\u25canh 24.3 \u00df\u201d ki\u201dm tra s\u02d8 ph\u00d9 thu\u00c8c c\u00d2a nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n v\u00cci ch\u2020t l\u00b5m v\u00c0t ng\u2260\u00cdi ta l\u00b5m th\u203a nghi\u00f7m sau \u00c6\u00a9y : D\u00d4ng \u00c6\u00c3n c\u00c2n \u00c6un n\u201eng 50g n\u2260\u00ccc v\u00b5 50g b\u00c8t b\u00aeng phi\u2019n c\u00d4ng n\u201eng th\u2122m l\u2122n 20oC (H.24.3). K\u2019t qu\u2202 th\u203a nghi\u00f7m \u00c6\u2260\u00d3c ghi \u00ce b\u2202ng 24.3. H\u2211y t\u25cam d\u2020u th\u203ach h\u00d3p (=; >; <) cho \u00b4 tr\u00cbng \u00ce c\u00c8t cu\u00cbi c\u00d2a b\u2202ng. B\u2202ng 24.3 Ch\u2020t Kh\u00cbi \u00df\u00c8 t\u00aeng Th\u00cdi gian So s\u220fnh l\u2260\u00d3ng nhi\u00f7t \u00c6\u00c8 \u00c6un nhi\u00f7t l\u2260\u00d3ng C\u00cbc 1 N\u2260\u00ccc C\u00cbc 2 B\u00aeng phi\u2019n 50g \uf044to1= 20oC t1= 5 ph\u00dbt Q1 Q2 50g \uf044to2= 20oC t2= 4 ph\u00dbt C6 Trong th\u203a nghi\u00f7m n\u00b5y nh\u02dcng y\u2019u t\u00cb n\u00b5o thay \u00c6\u00cai, kh\u00b4ng thay \u00c6\u00cai ? C7 Nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n c\u201e ph\u00d9 thu\u00c8c ch\u2020t l\u00b5m v\u00c0t kh\u00b4ng ? 85","II - c\u00b4ng th\u00afc t\u203anh nhi\u00f7t l\u2260\u00d3ng Nhi\u00f7t l\u2260\u00d3ng v\u00c0t thu v\u00b5o \u00c6\u2260\u00d3c t\u203anh theo c\u00b4ng th\u00afc Q = m.c.\uf044t trong \u00c6\u201e : Q l\u00b5 nhi\u00f7t l\u2260\u00d3ng v\u00c0t thu v\u00b5o, t\u203anh ra J, m l\u00b5 kh\u00cbi l\u2260\u00d3ng c\u00d2a v\u00c0t, t\u203anh ra kg, \uf044t = t2 - t1 l\u00b5 \u00c6\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8, t\u203anh ra oC ho\u2206c K*, c l\u00b5 \u00c6\u03c0i l\u2260\u00d3ng \u00c6\u2206c tr\u2260ng cho ch\u2020t l\u00b5m v\u00c0t g\u2030i l\u00b5 nhi\u00f7t dung ri\u2122ng, t\u203anh ra J\/kg.K. Nhi\u00f7t dung ri\u2122ng c\u00d2a m\u00c8t ch\u2020t cho bi\u2019t nhi\u00f7t l\u2260\u00d3ng c\u00abn truy\u201cn cho 1kg ch\u2020t \u00c6\u201e \u00c6\u201d nhi\u00f7t \u00c6\u00c8 t\u00aeng th\u2122m 1oC (1K). V\u203a d\u00d9, nhi\u00f7t dung ri\u2122ng c\u00d2a n\u2260\u00ccc l\u00b5 4 200J\/kg.K c\u201e ngh\u2039a l\u00b5 mu\u00cbn l\u00b5m cho 1kg n\u2260\u00ccc n\u201eng th\u2122m l\u2122n 1oC c\u00abn truy\u201cn cho n\u2260\u00ccc m\u00c8t nhi\u00f7t l\u2260\u00d3ng 4 200J. B\u2202ng 24.4 cho bi\u2019t nhi\u00f7t dung ri\u2122ng c\u00d2a m\u00c8t s\u00cb ch\u2020t. B\u2202ng 24.4 Ch\u2020t Nhi\u00f7t dung ri\u2122ng Ch\u2020t Nhi\u00f7t dung ri\u2122ng (J\/kg.K) (J\/kg.K) N\u2260\u00ccc 4 200 \u00df\u2020t 800 R\u2260\u00d3u 2 500 Th\u00e4p 460 N\u2260\u00ccc \u00c6\u220f 1 800 \u00df\u00c2ng 380 Nh\u00b4m 880 Ch\u25ca 130 iii - v\u00c0n d\u00d9ng C8 Mu\u00cbn x\u220fc \u00c6\ufb01nh nhi\u00f7t l\u2260\u00d3ng v\u00c0t thu v\u00b5o c\u00abn tra b\u2202ng \u00c6\u201d bi\u2019t \u00c6\u00c8 l\u00ccn c\u00d2a \u00c6\u03c0i l\u2260\u00d3ng n\u00b5o v\u00b5 \u00c6o \u00c6\u00c8 l\u00ccn c\u00d2a nh\u02dcng \u00c6\u03c0i l\u2260\u00d3ng n\u00b5o, b\u00aang nh\u02dcng d\u00d9ng c\u00d9 n\u00b5o ? C9 T\u203anh nhi\u00f7t l\u2260\u00d3ng c\u00abn truy\u201cn cho 5kg \u00c6\u00c2ng \u00c6\u201d t\u00aeng nhi\u00f7t \u00c6\u00c8 t\u0131 20oC l\u2122n 50oC. C10 M\u00c8t \u2020m \u00c6un n\u2260\u00ccc b\u00aang nh\u00b4m c\u201e kh\u00cbi l\u2260\u00d3ng 0,5kg ch\u00afa 2 l\u203at n\u2260\u00ccc \u00ce 25oC. Mu\u00cbn \u00c6un s\u00b4i \u2020m n\u2260\u00ccc n\u00b5y c\u00abn m\u00c8t nhi\u00f7t l\u2260\u00d3ng b\u00aang bao nhi\u2122u ? * K l\u00b5 \u00c6\u00a8n v\ufb01 nhi\u00f7t \u00c6\u00c8 trong thang nhi\u00f7t \u00c6\u00c8 Ken-vin : \u00df\u00c8 l\u00ccn c\u00d2a m\u00c8t \u00c6\u00c8 chia trong thang nhi\u00f7t \u00c6\u00c8 Ken-vin b\u00aang \u00c6\u00c8 l\u00ccn c\u00d2a m\u00c8t \u00c6\u00c8 chia trong thang nhi\u00f7t \u00c6\u00c8 Xen-xi-\u00dbt. 86","Nhi\u00f7t l\u2260\u00d3ng v\u00c0t c\u00abn thu v\u00b5o \u00c6\u201d n\u201eng l\u2122n ph\u00d9 thu\u00c8c kh\u00cbi l\u2260\u00d3ng, \u00c6\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8 c\u00d2a v\u00c0t v\u00b5 nhi\u00f7t dung ri\u2122ng c\u00d2a ch\u2020t l\u00b5m v\u00c0t. C\u00b4ng th\u00afc t\u203anh nhi\u00f7t l\u2260\u00d3ng v\u00c0t thu v\u00b5o Q = m.c.\uf044t, trong \u00c6\u201e : Q l\u00b5 nhi\u00f7t l\u2260\u00d3ng (J), m l\u00b5 kh\u00cbi l\u2260\u00d3ng c\u00d2a v\u00c0t (kg), \uf044t l\u00b5 \u00c6\u00c8 t\u00aeng nhi\u00f7t \u00c6\u00c8 c\u00d2a v\u00c0t (oC ho\u2206c K), c l\u00b5 nhi\u00f7t dung ri\u2122ng c\u00d2a ch\u2020t l\u00b5m v\u00c0t (J\/kg.K). Nhi\u00f7t dung ri\u2122ng c\u00d2a m\u00c8t ch\u2020t cho bi\u2019t nhi\u00f7t l\u2260\u00d3ng c\u00abn thi\u2019t \u00c6\u201d l\u00b5m cho 1kg ch\u2020t \u00c6\u201e t\u00aeng th\u2122m 1oC. C\u201e th\u201d em ch\u2260a bi\u2019t H\u25canh 24.4 H\u25canh 24.5 Trong k\u2039 thu\u00c0t v\u00b5 \u00c6\u00cdi s\u00cbng, ng\u2260\u00cdi ta c\ufb02n d\u00d4ng calo l\u00b5m \u00c6\u00a8n v\ufb01 nhi\u00f7t l\u2260\u00d3ng. Calo l\u00b5 nhi\u00f7t l\u2260\u00d3ng c\u00abn thi\u2019t \u00c6\u201d l\u00b5m cho 1 gam n\u2260\u00ccc \u00ce 4oC n\u201eng l\u2122n th\u2122m 1oC. Nh\u2260 v\u00c0y 1 calo = 4,2 jun. \u00df\u201d x\u220fc \u00c6\ufb01nh nhi\u00f7t l\u2260\u00d3ng trong ph\ufb02ng th\u203a nghi\u00f7m, ng\u2260\u00cdi ta d\u00d4ng m\u00c8t d\u00d9ng c\u00d9 ri\u2122ng g\u2030i l\u00b5 nhi\u00f7t l\u2260\u00d3ng k\u2019. Nhi\u00f7t l\u2260\u00d3ng k\u2019 l\u00b5 m\u00c8t b\u25canh hai v\u00b7, \u00ce gi\u02dca c\u201e m\u00c8t l\u00ccp kh\u00b4ng kh\u203a \u00c6\u201d ng\u00aen c\u2202n s\u02d8 truy\u201cn nhi\u00f7t c\u00d2a c\u220fc ch\u2020t \u00c6\u2206t trong b\u25canh v\u00cci m\u00b4i tr\u2260\u00cdng b\u2122n ngo\u00b5i. Trong b\u25canh c\u201e m\u00c8t nhi\u00f7t k\u2019 v\u00b5 m\u00c8t que khu\u2020y (H.24.4). Nhi\u00f7t dung ri\u2122ng c\u00d2a \u00c6\u2020t nh\u00b7 h\u00a8n nhi\u00f7t dung ri\u2122ng c\u00d2a n\u2260\u00ccc nhi\u201cu l\u00abn (xem b\u2202ng 24.4). Do \u00c6\u201e, ban ng\u00b5y khi nh\u00c0n \u00c6\u2260\u00d3c b\u00afc x\u03c0 nhi\u00f7t t\u0131 M\u2206t Tr\u00cdi, \u00c6\u2020t li\u201cn n\u201eng l\u2122n nhanh h\u00a8n n\u2260\u00ccc bi\u201dn. K\u2019t qu\u2202 l\u00b5 kh\u00b4ng kh\u203a tr\u2122n m\u2206t \u00c6\u2020t n\u201eng l\u2122n, nh\u00e3 \u00c6i, bay l\u2122n cao c\ufb02n kh\u00b4ng kh\u203a t\u0131 ngo\u00b5i bi\u201dn l\u03c0nh h\u00a8n di chuy\u201dn v\u00b5o \u00c6\u2020t li\u201cn t\u03c0o n\u2122n gi\u201e bi\u201dn (H.24.5). H\u2211y gi\u2202i th\u203ach t\u03c0i sao v\u201c \u00c6\u2122m gi\u201e l\u03c0i th\u00cai t\u0131 \u00c6\u2020t li\u201cn ra bi\u201dn ? 87","B\u00b5i 25 PH\u00b6\u2022NG TR\u00e7NH C\u00a2N B\u00d8NG NHI\u00e5T - Th\u220fi : \u00df\u00cb bi\u2019t khi nh\u00b7 m\u00c8t gi\u2030t n\u2260\u00ccc H\u25canh 25.1 s\u00b4i v\u00b5o m\u00c8t ca \u00c6\u02d8ng n\u2260\u00ccc n\u201eng th\u25ca gi\u2030t n\u2260\u00ccc truy\u201cn nhi\u00f7t cho ca n\u2260\u00ccc hay ca n\u2260\u00ccc truy\u201cn nhi\u00f7t cho gi\u2030t n\u2260\u00ccc (H.25.1) ? - B\u25canh : D\u2018 qu\u220f ! Nhi\u00f7t ph\u2202i truy\u201cn t\u0131 v\u00c0t c\u201e nhi\u00f7t n\u00aeng l\u00ccn h\u00a8n sang v\u00c0t c\u201e nhi\u00f7t n\u00aeng nh\u00b7 h\u00a8n, ngh\u2039a l\u00b5 t\u0131 ca n\u2260\u00ccc sang gi\u2030t n\u2260\u00ccc. - An : Kh\u00b4ng ph\u2202i ! Nhi\u00f7t ph\u2202i truy\u201cn t\u0131 v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 cao h\u00a8n sang v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 th\u2020p h\u00a8n, ngh\u2039a l\u00b5 t\u0131 gi\u2030t n\u2260\u00ccc sang ca n\u2260\u00ccc. Ai \u00c6\u00dbng, ai sai ? I - nguy\u2122n l\u203a truy\u201cn nhi\u00f7t C\u220fc th\u203a nghi\u00f7m c\u00dang nh\u2260 hi\u00f7n t\u2260\u00d3ng quan s\u220ft \u00c6\u2260\u00d3c trong \u00c6\u00cdi s\u00cbng, k\u2039 thu\u00c0t v\u00b5 t\u02d8 nhi\u2122n cho th\u2020y khi c\u201e hai v\u00c0t trao \u00c6\u00cai nhi\u00f7t v\u00cci nhau th\u25ca : 1. Nhi\u00f7t t\u02d8 truy\u201cn t\u0131 v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 cao h\u00a8n sang v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 th\u2020p h\u00a8n. 2. S\u02d8 truy\u201cn nhi\u00f7t x\u2202y ra cho t\u00cci khi nhi\u00f7t \u00c6\u00c8 c\u00d2a hai v\u00c0t b\u00aang nhau th\u25ca ng\u0131ng l\u03c0i. 3. Nhi\u00f7t l\u2260\u00d3ng do v\u00c0t n\u00b5y to\u2202 ra b\u00aang nhi\u00f7t l\u2260\u00d3ng do v\u00c0t kia thu v\u00b5o. II - Ph\u2260\u00a8ng tr\u25canh c\u00a9n b\u00aang nhi\u00f7t Ph\u2260\u00a8ng tr\u25canh c\u00a9n b\u00aang nhi\u00f7t \u00c6\u2260\u00d3c vi\u2019t d\u2260\u00cci d\u03c0ng Qto\u2202 ra = Qthu v\u00b5o Nhi\u00f7t l\u2260\u00d3ng to\u2202 ra c\u00dang \u00c6\u2260\u00d3c t\u203anh b\u00aang c\u00b4ng th\u00afc Q = m.c.\uf044t, nh\u2260ng trong \u00c6\u201e \uf044t = t1 - t2, v\u00cci t1 l\u00b5 nhi\u00f7t \u00c6\u00c8 ban \u00c6\u00abu c\ufb02n t2 l\u00b5 nhi\u00f7t \u00c6\u00c8 cu\u00cbi trong qu\u220f tr\u25canh truy\u201cn nhi\u00f7t. 88","III - V\u203a d\u00d9 v\u201c d\u00d4ng ph\u2260\u00a8ng tr\u25canh c\u00a9n b\u00aang nhi\u00f7t Th\u2202 m\u00c8t qu\u2202 c\u00abu nh\u00b4m kh\u00cbi l\u2260\u00d3ng 0,15kg \u00c6\u2260\u00d3c \u00c6un n\u201eng t\u00cci 100oC v\u00b5o m\u00c8t c\u00cbc n\u2260\u00ccc \u00ce 20oC. Sau m\u00c8t th\u00cdi gian, nhi\u00f7t \u00c6\u00c8 c\u00d2a qu\u2202 c\u00abu v\u00b5 c\u00d2a n\u2260\u00ccc \u00c6\u201cu b\u00aang 25oC. T\u203anh kh\u00cbi l\u2260\u00d3ng n\u2260\u00ccc, coi nh\u2260 ch\u00ff c\u201e qu\u2202 c\u00abu v\u00b5 n\u2260\u00ccc truy\u201cn nhi\u00f7t cho nhau. Cho bi\u2019t B\u00b5i gi\u2202i m1= 0,15kg Nhi\u00f7t l\u2260\u00d3ng qu\u2202 c\u00abu nh\u00b4m to\u2202 ra khi nhi\u00f7t \u00c6\u00c8 h\u03c0 t\u0131 100oC c1 = 880J\/kg.K xu\u00cbng 25oC l\u00b5 : t1 = 100oC t = 25oC Q1 = m1.c1.(t1 - t) = 0,15.880.(100 - 25) = 9 900J c2 = 4 200J\/kg.K Nhi\u00f7t l\u2260\u00d3ng n\u2260\u00ccc thu v\u00b5o khi t\u00aeng nhi\u00f7t \u00c6\u00c8 t\u0131 20oC l\u2122n t2 = 20oC 25oC l\u00b5 : t = 25oC Q2 = m2.c2.(t - t2) m2= ? Nhi\u00f7t l\u2260\u00d3ng qu\u2202 c\u00abu to\u2202 ra b\u00aang nhi\u00f7t l\u2260\u00d3ng n\u2260\u00ccc thu v\u00b5o : Q2 = Q1 m2.c2.(t - t2) = 9 900J m2 = 9 900 4 200.(25 - 20) m2 = 0,47kg. IV - v\u00c0n d\u00d9ng C1 a) H\u2211y d\u00d4ng ph\u2260\u00a8ng tr\u25canh c\u00a9n b\u00aang nhi\u00f7t \u00c6\u201d t\u203anh nhi\u00f7t \u00c6\u00c8 c\u00d2a h\u00c1n h\u00d3p g\u00c2m 200g n\u2260\u00ccc \u00c6ang s\u00b4i \u00c6\u00ca v\u00b5o 300g n\u2260\u00ccc \u00ce nhi\u00f7t \u00c6\u00c8 trong ph\ufb02ng. b) Ti\u2019n h\u00b5nh th\u203a nghi\u00f7m \u00c6\u201d ki\u201dm tra gi\u220f tr\ufb01 c\u00d2a nhi\u00f7t \u00c6\u00c8 t\u203anh \u00c6\u2260\u00d3c. Gi\u2202i th\u203ach t\u03c0i sao nhi\u00f7t \u00c6\u00c8 t\u203anh \u00c6\u2260\u00d3c kh\u00b4ng b\u00aang nhi\u00f7t \u00c6\u00c8 \u00c6o \u00c6\u2260\u00d3c ? C2 Ng\u2260\u00cdi ta th\u2202 m\u00c8t mi\u2019ng \u00c6\u00c2ng kh\u00cbi l\u2260\u00d3ng 0,5kg v\u00b5o 500g n\u2260\u00ccc. Mi\u2019ng \u00c6\u00c2ng ngu\u00c8i \u00c6i t\u0131 80oC xu\u00cbng 20oC. H\u00b7i n\u2260\u00ccc nh\u00c0n \u00c6\u2260\u00d3c m\u00c8t nhi\u00f7t l\u2260\u00d3ng b\u00aang bao nhi\u2122u v\u00b5 n\u201eng l\u2122n th\u2122m bao nhi\u2122u \u00c6\u00c8 ? C3 \u00df\u201d x\u220fc \u00c6\ufb01nh nhi\u00f7t dung ri\u2122ng c\u00d2a m\u00c8t kim lo\u03c0i, ng\u2260\u00cdi ta b\u00b7 v\u00b5o nhi\u00f7t l\u2260\u00d3ng k\u2019 ch\u00afa 500g n\u2260\u00ccc \u00ce nhi\u00f7t \u00c6\u00c8 13oC m\u00c8t mi\u2019ng kim lo\u03c0i c\u201e kh\u00cbi l\u2260\u00d3ng 400g \u00c6\u2260\u00d3c nung n\u201eng t\u00cci 100oC. Nhi\u00f7t \u00c6\u00c8 khi c\u201e c\u00a9n b\u00aang nhi\u00f7t l\u00b5 20oC. T\u203anh nhi\u00f7t dung ri\u2122ng c\u00d2a kim lo\u03c0i. B\u00b7 qua nhi\u00f7t l\u2260\u00d3ng l\u00b5m n\u201eng nhi\u00f7t l\u2260\u00d3ng k\u2019 v\u00b5 kh\u00b4ng kh\u203a. L\u2020y nhi\u00f7t dung ri\u2122ng c\u00d2a n\u2260\u00ccc l\u00b5 4 190J\/kg.K. 89","Khi c\u201e hai v\u00c0t truy\u201cn nhi\u00f7t cho nhau th\u25ca : + Nhi\u00f7t truy\u201cn t\u0131 v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 cao h\u00a8n sang v\u00c0t c\u201e nhi\u00f7t \u00c6\u00c8 th\u2020p h\u00a8n cho t\u00cci khi nhi\u00f7t \u00c6\u00c8 hai v\u00c0t b\u00aang nhau. + Nhi\u00f7t l\u2260\u00d3ng v\u00c0t n\u00b5y to\u2202 ra b\u00aang nhi\u00f7t l\u2260\u00d3ng v\u00c0t kia thu v\u00b5o. Ph\u2260\u00a8ng tr\u25canh c\u00a9n b\u00aang nhi\u00f7t : Qto\u2202 ra = Qthu v\u00b5o. C\u201e th\u201d em ch\u2260a bi\u2019t H\u25canh 25.2 C\u00a8 th\u201d con ng\u2260\u00cdi tuy kh\u00b4ng ng\u0131ng truy\u201cn nhi\u00f7t v\u00cci m\u00b4i tr\u2260\u00cdng b\u2122n ngo\u00b5i nh\u2260ng lu\u00b4n lu\u00b4n gi\u02dc nhi\u00f7t \u00c6\u00c8 kh\u00b4ng \u00c6\u00cai v\u00b5o kho\u2202ng 37oC d\u00d4 nhi\u00f7t \u00c6\u00c8 b\u2122n ngo\u00b5i c\u201e th\u201d gi\u2202m xu\u00cbng d\u2260\u00cci 0oC ho\u2206c t\u00aeng l\u2122n tr\u2122n 50oC. Nhi\u00f7t t\u0131 c\u00a8 th\u201d con ng\u2260\u00cdi c\u201e th\u201d truy\u201cn ra b\u2122n ngo\u00b5i b\u00aang nhi\u201cu c\u220fch trong \u00c6\u201e c\u201e d\u2026n nhi\u00f7t, \u00c6\u00cbi l\u2260u v\u00b5 b\u00afc x\u03c0. Trung b\u25canh c\u00a8 th\u201d con ng\u2260\u00cdi to\u2202 ra m\u00b4i tr\u2260\u00cdng b\u2122n ngo\u00b5i d\u2260\u00cci d\u03c0ng nhi\u00f7t kho\u2202ng 17% n\u00aeng l\u2260\u00d3ng m\u00b5 ng\u2260\u00cdi \u00c6\u201e t\u03c0o ra \u00c6\u2260\u00d3c. N\u2019u tr\u00cdi \u00bbm th\u25ca t\u00ff l\u00f7 n\u00b5y t\u00aeng l\u2122n. H\u25canh 25.2 cho th\u2020y t\u00ff l\u00f7 to\u2202 nhi\u00f7t d\u2260\u00cci c\u220fc h\u25canh th\u00afc d\u2026n nhi\u00f7t, \u00c6\u00cbi l\u2260u, b\u00afc x\u03c0 c\u00d2a m\u00c8t ng\u2260\u00cdi c\u00cei tr\u00abn, ng\u00c2i y\u2122n trong m\u00c8t ph\ufb02ng c\u201e nhi\u00f7t \u00c6\u00c8 \u00b4n ho\u00b5. 90","B\u00b5i 26 N\u00b0NG SU\u0192T To\u2202 NHI\u00e5T C\u00fbA NHI\u00a3N LI\u00e5U Nhi\u2122n li\u00f7u l\u00b5 g\u25ca ? T\u03c0i sao n\u201ei d\u00abu ho\u2202 l\u00b5 nhi\u2122n li\u00f7u t\u00cbt h\u00a8n than \u00c6\u220f, than \u00c6\u220f l\u00b5 nhi\u2122n li\u00f7u t\u00cbt h\u00a8n c\u00d2i ? H\u25canh 26.1 I - Nhi\u2122n li\u00f7u Trong \u00c6\u00cdi s\u00cbng v\u00b5 k\u2039 thu\u00c0t, ng\u2260\u00cdi ta ph\u2202i \u00c6\u00cbt than, c\u00d2i, d\u00abu... \u00c6\u201d cung c\u2020p nhi\u00f7t l\u2260\u00d3ng cho c\u220fc v\u00c0t li\u00f7u kh\u220fc. Than, c\u00d2i, d\u00abu... l\u00b5 c\u220fc nhi\u2122n li\u00f7u. H\u2211y t\u25cam th\u2122m ba v\u203a d\u00d9 v\u201c c\u220fc nhi\u2122n li\u00f7u th\u2260\u00cdng g\u2206p. II - N\u00aeng su\u2020t to\u00c5 nhi\u00f7t c\u00d2a nhi\u2122n li\u00f7u \u00df\u03c0i l\u2260\u00d3ng v\u00c0t l\u203a cho bi\u2019t nhi\u00f7t l\u2260\u00d3ng to\u2202 ra khi 1kg nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n \u00c6\u2260\u00d3c g\u2030i l\u00b5 n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a nhi\u2122n li\u00f7u. N\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a nhi\u2122n li\u00f7u \u00c6\u2260\u00d3c k\u203a hi\u00f7u b\u00aang ch\u02dc q v\u00b5 c\u201e \u00c6\u00a8n v\ufb01 l\u00b5 J\/kg. V\u203a d\u00d9, n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a d\u00abu ho\u2202 l\u00b5 44.106J\/kg c\u201e ngh\u2039a l\u00b5 1kg d\u00abu ho\u2202 b\ufb01 \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n to\u2202 ra nhi\u00f7t l\u2260\u00d3ng b\u00aang 44.106J. B\u2202ng 26.1 cho bi\u2019t n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a m\u00c8t s\u00cb nhi\u2122n li\u00f7u. B\u2202ng 26.1 Ch\u2020t N\u00aeng su\u2020t Ch\u2020t N\u00aeng su\u2020t to\u2202 nhi\u00f7t (J\/kg) to\u2202 nhi\u00f7t (J\/kg) C\u00d2i kh\u00b4 Kh\u203a \u00c6\u00cbt Than b\u00d4n 10.106 D\u00abu ho\u2202 44.106 Than \u00c6\u220f 14.106 44.106 Than g\u00c1 27.106 X\u00aeng 46.106 34.106 Hi\u00c6r\u00b4 120.106 91","III - C\u00b4ng th\u00afc t\u203anh nhi\u00f7t l\u2260\u00d3ng do nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy to\u00c5 ra Nhi\u00f7t l\u2260\u00d3ng to\u2202 ra khi \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n m kg nhi\u2122n li\u00f7u \u00c6\u2260\u00d3c t\u203anh b\u00aang c\u00b4ng th\u00afc Q = q.m, trong \u00c6\u201e : Q l\u00b5 nhi\u00f7t l\u2260\u00d3ng to\u2202 ra (J), q l\u00b5 n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a nhi\u2122n li\u00f7u (J\/kg), m l\u00b5 kh\u00cbi l\u2260\u00d3ng c\u00d2a nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n (kg). IV - V\u00c0n d\u00d9ng C1 H\u2211y cho bi\u2019t n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a kh\u203a \u00c6\u00cbt b\u00aang bao nhi\u2122u l\u00abn n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a than b\u00d4n ? C2 T\u203anh nhi\u00f7t l\u2260\u00d3ng to\u2202 ra khi \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n 15kg c\u00d2i, 15kg than \u00c6\u220f. \u00df\u201d thu \u00c6\u2260\u00d3c m\u00c1i nhi\u00f7t l\u2260\u00d3ng tr\u2122n c\u00abn \u00c6\u00cbt ch\u220fy h\u2019t bao nhi\u2122u kg d\u00abu ho\u2202 ? \u00df\u03c0i l\u2260\u00d3ng cho bi\u2019t nhi\u00f7t l\u2260\u00d3ng to\u2202 ra khi 1kg nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n g\u2030i l\u00b5 n\u00aeng su\u2020t to\u2202 nhi\u00f7t c\u00d2a nhi\u2122n li\u00f7u. \u00df\u00a8n v\ufb01 c\u00d2a n\u00aeng su\u2020t to\u2202 nhi\u00f7t l\u00b5 J\/kg. C\u00b4ng th\u00afc t\u203anh nhi\u00f7t l\u2260\u00d3ng to\u2202 ra khi nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy ho\u00b5n to\u00b5n : Q = q.m. C\u201e th\u201d em ch\u2260a bi\u2019t H\u25canh 26.2 Khai th\u220fc d\u00abu v\u00b5 kh\u203a \u00c6\u00cbt \u00ce V\u00dang T\u00b5u. D\u00abu v\u00b5 kh\u203a \u00c6\u00cbt t\u02d8 nhi\u2122n hi\u00f7n \u00c6ang l\u00b5 c\u220fc nhi\u2122n li\u00f7u ch\u00d2 y\u2019u c\u00d2a con ng\u2260\u00cdi. Theo \u2260\u00ccc t\u203anh th\u25ca Tr\u220fi \u00df\u2020t ch\u00ff c\ufb02n d\u02d8 tr\u02dc kho\u2202ng 140 t\u00ff t\u2020n d\u00abu v\u00b5 100 000 t\u00ff m3 kh\u203a \u00c6\u00cbt. V\u00cci nh\ufb01p \u00c6\u00c8 d\u00d4ng d\u00abu v\u00b5 kh\u203a \u00c6\u00cbt nh\u2260 hi\u00f7n nay th\u25ca ch\u00ff trong v\ufb02ng n\u00aem m\u2260\u00a8i n\u00aem n\u02dca l\u00b5 c\u220fc ngu\u00c2n d\u02d8 tr\u02dc tr\u2122n s\u0153 c\u03c0n ki\u00f7t. Do \u00c6\u201e, m\u00c8t trong nh\u02dcng v\u2020n \u00c6\u201c s\u00cbng c\ufb02n c\u00d2a con ng\u2260\u00cdi l\u00b5 ph\u2202i ti\u2019t ki\u00f7m c\u220fc nhi\u2122n li\u00f7u s\u2126n c\u201e, \u00c6\u00c2ng th\u00cdi \u00c6i t\u25cam c\u220fc nhi\u2122n li\u00f7u m\u00cci. 92","M\u00c8t trong nh\u02dcng nhi\u2122n li\u00f7u c\u201e tri\u201dn v\u2030ng thay th\u2019 cho d\u00abu v\u00b5 kh\u203a \u00c6\u00cbt l\u00b5 hi\u00c6r\u00b4 v\u25ca : + Hi\u00c6r\u00b4 c\u201e n\u00aeng su\u2020t to\u2202 nhi\u00f7t cao h\u00a8n d\u00abu v\u00b5 kh\u203a \u00c6\u00cbt (xem b\u2202ng 26.1). + Hi\u00c6r\u00b4 c\u201e th\u201d \u00c6\u2260\u00d3c \u00c6i\u201cu ch\u2019 b\u00aang c\u220fch d\u00d4ng n\u00aeng l\u2260\u00d3ng m\u2206t tr\u00cdi \u00c6\u201d \u00c6i\u00f7n ph\u00a9n n\u2260\u00ccc bi\u201dn. Nh\u2260 v\u00c0y, ngu\u00c2n nguy\u2122n li\u00f7u \u00c6\u201d \u00c6i\u201cu ch\u2019 hi\u00c6r\u00b4 c\u201e th\u201d coi nh\u2260 v\u00b4 t\u00c0n. + Hi\u00c6r\u00b4 l\u00b7ng c\u201e th\u201d \u00c6\u2260\u00d3c chuy\u2122n ch\u00ce b\u00aang c\u220fc b\u25canh ch\u00afa ho\u2206c \u00cbng d\u2026n. + Hi\u00c6r\u00b4 khi b\ufb01 \u00c6\u00cbt ch\u220fy kh\u00b4ng to\u2202 ra c\u220fc kh\u203a \u00c6\u00c8c nh\u2260 c\u220fc nhi\u2122n li\u00f7u kh\u220fc n\u2122n kh\u00b4ng l\u00b5m \u00b4 nhi\u2018m m\u00b4i tr\u2260\u00cdng. H\u25canh 26.3 cho ta th\u2020y l\u2260\u00d3ng d\u00abu ti\u2122u th\u00d9, s\u2202n xu\u2020t v\u00b5 d\u02d8 tr\u02dc tr\u2122n th\u2019 gi\u00cci t\u203anh theo tri\u00f7u t\u2020n v\u00b5o n\u00aem 2000. H\u25canh 26.3 93","B\u00b5i 27 S# B\u00c5O TO\u00c4N N\u00b0NG L\u00b6\u00faNG TRONG C\u00c9C HI\u00e5N T\u00b6\u00faNG C\u2022 V\u00c4 NHI\u00e5T Trong c\u220fc hi\u00f7n t\u2260\u00d3ng c\u00a8 v\u00b5 nhi\u00f7t lu\u00b4n lu\u00b4n x\u2202y ra s\u02d8 truy\u201cn c\u00a8 n\u00aeng, nhi\u00f7t n\u00aeng t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc ; s\u02d8 chuy\u201dn ho\u220f gi\u02dca c\u220fc d\u03c0ng c\u00d2a c\u00a8 n\u00aeng c\u00dang nh\u2260 gi\u02dca c\u00a8 n\u00aeng v\u00b5 nhi\u00f7t n\u00aeng. Trong khi truy\u201cn t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc, chuy\u201dn ho\u220f t\u0131 d\u03c0ng n\u00b5y sang d\u03c0ng kh\u220fc, c\u220fc n\u00aeng l\u2260\u00d3ng tr\u2122n tu\u00a9n theo m\u00c8t trong nh\u02dcng \u00c6\ufb01nh lu\u00c0t t\u00cang qu\u220ft nh\u2020t c\u00d2a t\u02d8 nhi\u2122n m\u00b5 ch\u00dbng ta s\u0153 h\u2030c trong b\u00b5i n\u00b5y. I - S\u02d8 truy\u201cn c\u00a8 n\u00aeng, nhi\u00f7t n\u00aeng t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc C1 H\u2211y m\u00b4 t\u2202 s\u02d8 truy\u201cn c\u00a8 n\u00aeng, nhi\u00f7t n\u00aeng trong c\u220fc hi\u00f7n t\u2260\u00d3ng sau \u00c6\u00a9y v\u00b5 t\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a c\u220fc c\u00a9u \u00ce c\u00c8t b\u2122n ph\u2202i b\u2202ng 27.1 B\u2202ng 27.1 Hi\u00f7n t\u2260\u00d3ng S\u02d8 truy\u201cn n\u00aeng l\u2260\u00d3ng H\ufb02n bi truy\u201cn ....(1).... cho mi\u2019ng g\u00c1. H\ufb02n bi th\u00e4p l\u00aen t\u0131 m\u220fng nghi\u2122ng xu\u00cbng va ch\u03c0m v\u00b5o mi\u2019ng g\u00c1 l\u00b5m mi\u2019ng g\u00c1 chuy\u201dn \u00c6\u00c8ng. Th\u2202 m\u00c8t mi\u2019ng Mi\u2019ng nh\u00b4m truy\u201cn nh\u00b4m \u00c6\u2211 \u00c6\u2260\u00d3c nung ....(2).... cho c\u00cbc n\u2260\u00ccc. n\u201eng v\u00b5o m\u00c8t c\u00cbc n\u2260\u00ccc l\u03c0nh. Vi\u2122n \u00c6\u03c0n t\u0131 n\ufb02ng Vi\u2122n \u00c6\u03c0n truy\u201cn s\u00dbng bay ra, r\u00a8i ....(3).... v\u00b5 ....(4).... xu\u00cbng bi\u201dn, ngu\u00c8i \u00c6i cho n\u2260\u00ccc bi\u201dn. v\u00b5 ch\u25cam d\u00abn. 94","II - S\u02d8 chuy\u201dn ho\u220f gi\u02dca c\u220fc d\u03c0ng c\u00d2a c\u00a8 n\u00aeng, gi\u02dca c\u00a8 n\u00aeng v\u00b5 nhi\u00f7t n\u00aeng C2 H\u2211y m\u00b4 t\u2202 s\u02d8 chuy\u201dn ho\u220f n\u00aeng l\u2260\u00d3ng trong c\u220fc hi\u00f7n t\u2260\u00d3ng sau \u00c6\u00a9y v\u00b5 t\u25cam t\u0131 th\u203ach h\u00d3p cho c\u220fc ch\u00c1 tr\u00cbng c\u00d2a c\u220fc c\u00a9u \u00ce c\u00c8t b\u2122n ph\u2202i b\u2202ng 27.2. B\u2202ng 27.2 Hi\u00f7n t\u2260\u00d3ng S\u02d8 chuy\u201dn ho\u220f n\u00aeng l\u2260\u00d3ng Khi b\u00b7 tay gi\u02dc con Khi con l\u00e6c chuy\u201dn l\u00e6c, con l\u00e6c chuy\u201dn \u00c6\u00c8ng t\u0131 A \u00c6\u2019n B \u00c6\u00c8ng nhanh d\u00abn t\u0131 ....(5).... \u00c6\u2211 chuy\u201dn ho\u220f A \u00c6\u2019n B, ch\u00c0m d\u00abn t\u0131 d\u00abn th\u00b5nh ....(6)..... B \u00c6\u2019n C, r\u00c2i l\u03c0i Khi con l\u00e6c chuy\u201dn chuy\u201dn \u00c6\u00c8ng nhanh \u00c6\u00c8ng t\u0131 B \u00c6\u2019n C d\u00abn t\u0131 C \u00c6\u2019n B, ch\u00c0m ....(7).... \u00c6\u2211 chuy\u201dn d\u00abn t\u0131 B \u00c6\u2019n A... ho\u220f d\u00abn th\u00b5nh ....(8).... D\u00d4ng tay c\u2030 x\u220ft ....(9).... c\u00d2a tay \u00c6\u2211 mi\u2019ng \u00c6\u00c2ng l\u2122n m\u2206t chuy\u201dn ho\u220f th\u00b5nh b\u00b5n, mi\u2019ng \u00c6\u00c2ng ....(10).... c\u00d2a mi\u2019ng n\u201eng l\u2122n. kim lo\u03c0i. \u00dfun n\u201eng \u00cbng ....(11).... c\u00d2a kh\u00b4ng nghi\u00f7m. Kh\u00b4ng kh\u203a kh\u203a v\u00b5 h\u00a8i n\u2260\u00ccc \u00c6\u2211 v\u00b5 h\u00a8i n\u2260\u00ccc trong chuy\u201dn ho\u220f th\u00b5nh \u00cbng nghi\u00f7m n\u201eng ....(12).... c\u00d2a n\u00dbt. l\u2122n, d\u2211n n\u00ce, \u00c6\u00bby n\u00dbt b\u00c0t l\u2122n v\u00b5 l\u03c0nh \u00c6i. III - S\u02d8 b\u2202o to\u00b5n n\u00aeng l\u2260\u00d3ng trong c\u220fc hi\u00f7n t\u2260\u00d3ng c\u00a8 v\u00b5 nhi\u00f7t B\u00aang nh\u02dcng quan s\u220ft v\u00b5 th\u203a nghi\u00f7m ch\u203anh x\u220fc, ng\u2260\u00cdi ta \u00c6\u2211 ch\u00afng t\u00b7 \u00c6\u2260\u00d3c l\u00b5 trong c\u220fc hi\u00f7n t\u2260\u00d3ng c\u00a8 v\u00b5 nhi\u00f7t : \\\"N\u00aeng l\u2260\u00d3ng kh\u00b4ng t\u02d8 sinh ra c\u00dang kh\u00b4ng t\u02d8 m\u2020t \u00c6i ; n\u201e ch\u00ff truy\u201cn t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc, chuy\u201dn ho\u220f t\u0131 d\u03c0ng n\u00b5y sang d\u03c0ng kh\u220fc\\\". 95","\u00df\u201e ch\u203anh l\u00b5 n\u00c8i dung c\u00d2a \u00c6\ufb01nh lu\u00c0t b\u2202o to\u00b5n v\u00b5 chuy\u201dn ho\u220f n\u00aeng l\u2260\u00d3ng, m\u00c8t trong nh\u02dcng \u00c6\ufb01nh lu\u00c0t t\u00cang qu\u220ft nh\u2020t c\u00d2a t\u02d8 nhi\u2122n. C3 H\u2211y t\u25cam v\u203a d\u00d9 v\u201c s\u02d8 bi\u201du hi\u00f7n c\u00d2a \u00c6\ufb01nh lu\u00c0t tr\u2122n trong c\u220fc hi\u00f7n t\u2260\u00d3ng c\u00a8 v\u00b5 nhi\u00f7t \u00c6\u2211 h\u2030c. IV - V\u00c0n d\u00d9ng C4 H\u2211y t\u25cam th\u2122m v\u203a d\u00d9, ngo\u00b5i nh\u02dcng v\u203a d\u00d9 \u00c6\u2211 c\u201e trong b\u00b5i v\u201c s\u02d8 truy\u201cn c\u00a8 n\u00aeng, nhi\u00f7t n\u00aeng t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc ; s\u02d8 chuy\u201dn ho\u220f gi\u02dca c\u220fc d\u03c0ng c\u00d2a c\u00a8 n\u00aeng c\u00dang nh\u2260 gi\u02dca nhi\u00f7t n\u00aeng v\u00b5 c\u00a8 n\u00aeng. C5 T\u03c0i sao trong hi\u00f7n t\u2260\u00d3ng h\ufb02n C6 T\u03c0i sao trong hi\u00f7n t\u2260\u00d3ng v\u201c dao bi va v\u00b5o thanh g\u00c1, c\u2202 h\ufb02n bi v\u00b5 \u00c6\u00c8ng c\u00d2a con l\u00e6c, con l\u00e6c ch\u00ff dao thanh g\u00c1 sau khi va ch\u03c0m ch\u00ff \u00c6\u00c8ng trong m\u00c8t th\u00cdi gian ng\u00e6n r\u00c2i chuy\u201dn \u00c6\u00c8ng \u00c6\u2260\u00d3c m\u00c8t \u00c6o\u03c0n ng\u00e6n d\u0131ng l\u03c0i \u00ce v\ufb01 tr\u203a c\u00a9n b\u00aang ? C\u00a8 n\u00aeng r\u00c2i d\u0131ng l\u03c0i. C\u00a8 n\u00aeng c\u00d2a ch\u00dbng \u00c6\u2211 c\u00d2a con l\u00e6c \u00c6\u2211 chuy\u201dn ho\u220f th\u00b5nh bi\u2019n \u00c6i \u00c6\u00a9u ? d\u03c0ng n\u00aeng l\u2260\u00d3ng n\u00b5o ? C\u00a8 n\u00aeng, nhi\u00f7t n\u00aeng c\u201e th\u201d truy\u201cn t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc, chuy\u201dn ho\u220f t\u0131 d\u03c0ng n\u00b5y sang d\u03c0ng kh\u220fc. \u00df\ufb01nh lu\u00c0t b\u2202o to\u00b5n v\u00b5 chuy\u201dn ho\u220f n\u00aeng l\u2260\u00d3ng : N\u00aeng l\u2260\u00d3ng kh\u00b4ng t\u02d8 sinh ra c\u00dang kh\u00b4ng t\u02d8 m\u2020t \u00c6i ; n\u201e ch\u00ff truy\u201cn t\u0131 v\u00c0t n\u00b5y sang v\u00c0t kh\u220fc, chuy\u201dn ho\u220f t\u0131 d\u03c0ng n\u00b5y sang d\u03c0ng kh\u220fc. C\u201e th\u201d em ch\u2260a bi\u2019t T\u0131 n\u00aem 1840 \u00c6\u2019n n\u00aem 1849, nh\u00b5 b\u220fc h\u2030c Jun (1818 - 1889) ng\u2260\u00cdi Anh \u00c6\u2211 l\u00b5m nhi\u201cu th\u203a nghi\u00f7m \u00c6\u201d ch\u00afng minh s\u02d8 t\u2260\u00a8ng \u00c6\u2260\u00a8ng gi\u02dca c\u00b4ng v\u00b5 nhi\u00f7t l\u2260\u00d3ng, ngh\u2039a l\u00b5 ch\u00afng minh s\u02d8 b\u2202o to\u00b5n n\u00aeng l\u2260\u00d3ng trong c\u220fc hi\u00f7n t\u2260\u00d3ng c\u00a8 v\u00b5 nhi\u00f7t. Sau \u00c6\u00a9y l\u00b5 m\u00c8t trong nh\u02dcng th\u203a nghi\u00f7m n\u00cai ti\u2019ng nh\u2020t c\u00d2a \u00b4ng (H.27.1). Khi c\u220fc v\u00c0t n\u2206ng M r\u00a8i xu\u00cbng, ch\u00dbng th\u02d8c hi\u00f7n H\u25canh 27.1 c\u00b4ng l\u00b5m quay c\u220fc l\u220f kim lo\u03c0i L \u00c6\u2206t trong n\u2260\u00ccc, do \u00c6\u201e l\u00b5m cho n\u2260\u00ccc n\u201eng l\u2122n. C\u220fc ph\u00e4p \u00c6o ch\u203anh x\u220fc cho th\u2020y c\u00b4ng do c\u220fc qu\u2202 n\u2206ng th\u02d8c hi\u00f7n \u00c6\u2260\u00d3c \u00c6\u00dbng b\u00aang nhi\u00f7t l\u2260\u00d3ng m\u00b5 n\u2260\u00ccc nh\u00c0n \u00c6\u2260\u00d3c, ngh\u2039a l\u00b5 c\u00a8 n\u00aeng c\u00d2a c\u220fc qu\u2202 n\u2206ng gi\u2202m \u00c6i bao nhi\u2122u th\u25ca nhi\u00f7t n\u00aeng c\u00d2a n\u2260\u00ccc t\u00aeng l\u2122n b\u2020y nhi\u2122u. 96","B\u00b5i 28 \u00df\u00f3NG C\u2022 NHI\u00e5T K\u201d t\u0131 chi\u2019c m\u220fy h\u00a8i n\u2260\u00ccc \u00c6\u00abu ti\u2122n \u00c6\u2260\u00d3c ch\u2019 t\u03c0o v\u00b5o cu\u00cbi th\u2019 k\u00ff XVII, v\u0131a c\u00c2ng k\u201cnh v\u0131a ch\u00ff s\u02c6 d\u00d9ng \u00c6\u2260\u00d3c kh\u00b4ng qu\u220f 5% n\u00aeng l\u2260\u00d3ng c\u00d2a nhi\u2122n li\u00f7u \u00c6\u2260\u00d3c \u00c6\u00cbt ch\u220fy, \u00c6\u2019n nay con ng\u2260\u00cdi \u00c6\u2211 c\u201e nh\u02dcng b\u2260\u00ccc ti\u2019n kh\u00cang l\u00c2 trong l\u2039nh v\u02d8c ch\u2019 t\u03c0o \u00c6\u00c8ng c\u00a8 nhi\u00f7t. Ng\u00b5y nay, con ng\u2260\u00cdi s\u02c6 d\u00d9ng t\u0131 nh\u02dcng \u00c6\u00c8ng c\u00a8 nhi\u00f7t b\u00e4 nh\u00b7 d\u00d4ng \u00c6\u201d ch\u03c0y xe g\u00e6n m\u220fy \u00c6\u2019n nh\u02dcng \u00c6\u00c8ng c\u00a8 nhi\u00f7t kh\u00cang l\u00c2 d\u00d4ng \u00c6\u201d ph\u201eng nh\u02dcng con t\u00b5u v\u00da tr\u00d9. I - \u00df\u00c8ng c\u00a8 nhi\u00f7t l\u00b5 g\u25ca ? \u00df\u00c8ng c\u00a8 nhi\u00f7t l\u00b5 nh\u02dcng \u00c6\u00c8ng c\u00a8 trong \u00c6\u201e m\u00c8t ph\u00abn n\u00aeng l\u2260\u00d3ng c\u00d2a nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy \u00c6\u2260\u00d3c chuy\u201dn ho\u220f th\u00b5nh c\u00a8 n\u00aeng. C\u220fc \u00c6\u00c8ng c\u00a8 nhi\u00f7t \u00c6\u00abu ti\u2122n l\u00b5 c\u220fc m\u220fy h\u00a8i n\u2260\u00ccc (H.28.1). Ch\u00dbng c\u201e \u00c6\u2206c \u00c6i\u201dm chung l\u00b5 nhi\u2122n li\u00f7u (c\u00d2i, than, d\u00abu...) \u00c6\u2260\u00d3c \u00c6\u00cbt ch\u220fy \u00ce b\u2122n ngo\u00b5i xilanh c\u00d2a \u00c6\u00c8ng c\u00a8. H\u00b5ng tr\u00aem n\u00aem sau khi m\u220fy h\u00a8i n\u2260\u00ccc ra \u00c6\u00cdi m\u00cci xu\u2020t hi\u00f7n \u00c6\u00c8ng c\u00a8 \u00c6\u00cbt trong, l\u00b5 \u00c6\u00c8ng c\u00a8 nhi\u00f7t m\u00b5 nhi\u2122n li\u00f7u \u00c6\u2260\u00d3c \u00c6\u00cbt ch\u220fy ngay \u00ce b\u2122n trong xilanh. \u00df\u00c8ng c\u00a8 nhi\u00f7t l\u00b5 \u00c6\u00c8ng c\u00a8 \u00c6\u2260\u00d3c s\u02c6 d\u00d9ng r\u00c8ng r\u2211i nh\u2020t hi\u00f7n nay, bao g\u00c2m t\u0131 nh\u02dcng \u00c6\u00c8ng c\u00a8 ch\u03c0y b\u00aang x\u00aeng ho\u2206c d\u00abu ma d\u00dbt c\u00d2a xe m\u220fy, \u00b4t\u00b4 (H.28.2), m\u220fy bay, t\u00b5u ho\u2202, t\u00b5u thu\u02da... \u00c6\u2019n c\u220fc \u00c6\u00c8ng c\u00a8 ch\u03c0y b\u00aang c\u220fc nhi\u2122n li\u00f7u \u00c6\u2206c bi\u00f7t c\u00d2a t\u2122n l\u02c6a, con t\u00b5u v\u00da tr\u00d9 (H.28.3), \u00c6\u00c8ng c\u00a8 ch\u03c0y b\u00aang n\u00aeng l\u2260\u00d3ng nguy\u2122n t\u02c6 c\u00d2a t\u00b5u ng\u00abm, t\u00b5u ph\u220f b\u00aeng, nh\u00b5 m\u220fy \u00c6i\u00f7n nguy\u2122n t\u02c6... H\u25canh 28.1 H\u25canh 28.2 H\u25canh 28.3 97","II - \u00df\u00c8ng c\u00a8 n\u00ca b\u00cbn k\u25ca \u00df\u00c8ng c\u00a8 n\u00ca b\u00cbn k\u25ca l\u00b5 \u00c6\u00c8ng c\u00a8 nhi\u00f7t th\u2260\u00cdng g\u2206p nh\u2020t hi\u00f7n nay. 1. C\u2020u t\u03c0o \u00df\u00c8ng c\u00a8 g\u00c2m xilanh, trong c\u201e pit-t\u00b4ng (3) chuy\u201dn \u00c6\u00c8ng l\u2122n xu\u00cbng \u00c6\u2260\u00d3c. Pit-t\u00b4ng \u00c6\u2260\u00d3c n\u00cbi v\u00cci tr\u00d9c b\u00aang bi\u2122n (4) v\u00b5 tay quay (5). Tr\u2122n tr\u00d9c quay c\u201e g\u00e6n v\u00b4 l\u00aeng (6). Ph\u203aa tr\u2122n xilanh c\u201e hai van (xupap) (1) v\u00b5 (2) c\u201e th\u201d t\u02d8 \u00c6\u00c8ng \u00c6\u201eng, m\u00ce khi pit-t\u00b4ng chuy\u201dn \u00c6\u00c8ng. \u00f4 tr\u2122n xilanh c\u201e bugi (7) d\u00d4ng \u00c6\u201d b\u00c0t tia l\u02c6a \u00c6i\u00f7n, \u00c6\u00cbt ch\u220fy nhi\u2122n li\u00f7u trong xilanh (H.28.4). H\u25canh 28.4 2. Chuy\u201dn v\u00c0n a) K\u25ca th\u00af nh\u2020t : H\u00dbt nhi\u2122n li\u00f7u. Pit-t\u00b4ng chuy\u201dn \u00c6\u00c8ng xu\u00cbng d\u2260\u00cci. Van (1) m\u00ce, van (2) \u00c6\u201eng, h\u00c1n h\u00d3p nhi\u2122n li\u00f7u \u00c6\u2260\u00d3c h\u00dbt v\u00b5o xilanh. Cu\u00cbi k\u25ca n\u00b5y xilanh \u00c6\u2211 ch\u00afa \u00c6\u00aby h\u00c1n h\u00d3p nhi\u2122n li\u00f7u v\u00b5 van (1) \u00c6\u201eng l\u03c0i (H.28.5a). b) K\u25ca th\u00af hai : N\u00e4n nhi\u2122n li\u00f7u. Pit-t\u00b4ng chuy\u201dn \u00c6\u00c8ng l\u2122n ph\u203aa tr\u2122n n\u00e4n h\u00c1n h\u00d3p nhi\u2122n li\u00f7u trong xilanh (H.28.5b). a) b) c) d) H\u25canh 28.5 c) K\u25ca th\u00af ba : \u00df\u00cbt nhi\u2122n li\u00f7u. Khi pit-t\u00b4ng l\u2122n \u00c6\u2019n t\u00c0n c\u00d4ng th\u25ca bugi b\u00c0t tia l\u02c6a \u00c6i\u00f7n \u00c6\u00cbt ch\u220fy h\u00c1n h\u00d3p nhi\u2122n li\u00f7u, k\u00c3m theo ti\u2019ng n\u00ca v\u00b5 to\u2202 nhi\u00f7t. C\u220fc ch\u2020t kh\u203a m\u00cci t\u03c0o th\u00b5nh d\u2211n n\u00ce, sinh c\u00b4ng \u00c6\u00bby pit-t\u00b4ng xu\u00cbng d\u2260\u00cci. Cu\u00cbi k\u25ca n\u00b5y van (2) m\u00ce ra (H.28.5c). d) K\u25ca th\u00af t\u2260 : Tho\u220ft kh\u203a. Pit-t\u00b4ng chuy\u201dn \u00c6\u00c8ng l\u2122n ph\u203aa tr\u2122n, d\u00c2n h\u2019t kh\u203a trong xilanh ra ngo\u00b5i qua van (2) (H.28.5d). Sau \u00c6\u201e c\u220fc k\u25ca c\u00d2a \u00c6\u00c8ng c\u00a8 l\u03c0i \u00c6\u2260\u00d3c l\u2206p l\u03c0i. Trong b\u00cbn k\u25ca, ch\u00ff c\u201e k\u25ca th\u00af ba l\u00b5 k\u25ca \u00c6\u00c8ng c\u00a8 sinh c\u00b4ng. \u00f4 c\u220fc k\u25ca kh\u220fc, \u00c6\u00c8ng c\u00a8 chuy\u201dn \u00c6\u00c8ng nh\u00cd \u00c6\u00b5 c\u00d2a v\u00b4 l\u00aeng. 98","III - Hi\u00f7u su\u2020t c\u00d2a \u00c6\u00c8ng c\u00a8 nhi\u00f7t C1 \u00f4 \u00c6\u00c8ng c\u00a8 n\u00ca b\u00cbn k\u25ca c\u00dang nh\u2260 \u00ce b\u2020t k\u25ca \u00c6\u00c8ng c\u00a8 nhi\u00f7t n\u00b5o c\u201e ph\u2202i to\u00b5n b\u00c8 nhi\u00f7t l\u2260\u00d3ng c\u00d2a nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy to\u2202 ra \u00c6\u2260\u00d3c bi\u2019n th\u00b5nh c\u00b4ng c\u201e \u203ach kh\u00b4ng ? T\u03c0i sao ? C2 Trong th\u02d8c t\u2019 ch\u00ff c\u201e kho\u2202ng t\u0131 30% \u00c6\u2019n 40% nhi\u00f7t l\u2260\u00d3ng do nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy to\u2202 ra \u00c6\u2260\u00d3c bi\u2019n th\u00b5nh c\u00b4ng c\u201e \u203ach. Ng\u2260\u00cdi ta n\u201ei c\u220fc \u00c6\u00c8ng c\u00a8 nhi\u00f7t c\u201e hi\u00f7u su\u2020t v\u00b5o kho\u2202ng t\u0131 30% \u00c6\u2019n 40% v\u00b5 \u00c6\u2260a ra c\u00b4ng th\u00afc t\u203anh hi\u00f7u su\u2020t A H= Q H\u2211y ph\u220ft bi\u201du \u00c6\ufb01nh ngh\u2039a hi\u00f7u su\u2020t c\u00d2a \u00c6\u00c8ng c\u00a8 nhi\u00f7t v\u00b5 n\u2122u t\u2122n, \u00c6\u00a8n v\ufb01 c\u00d2a c\u220fc \u00c6\u03c0i l\u2260\u00d3ng c\u201e m\u2206t trong bi\u201du th\u00afc tr\u2122n. IV - V\u00c0n d\u00d9ng C3 C\u220fc m\u220fy c\u00a8 \u00c6\u00a8n gi\u2202n h\u2030c \u00ce l\u00ccp 6 c\u201e ph\u2202i l\u00b5 \u00c6\u00c8ng c\u00a8 nhi\u00f7t kh\u00b4ng ? T\u03c0i sao ? C4 H\u2211y k\u201d t\u2122n c\u220fc d\u00d9ng c\u00d9 c\u201e s\u02c6 d\u00d9ng \u00c6\u00c8ng c\u00a8 n\u00ca b\u00cbn k\u25ca m\u00b5 em bi\u2019t. C5 Theo em th\u25ca \u00c6\u00c8ng c\u00a8 nhi\u00f7t c\u201e th\u201d g\u00a9y ra nh\u02dcng t\u220fc h\u03c0i n\u00b5o \u00c6\u00cbi v\u00cci m\u00b4i tr\u2260\u00cdng s\u00cbng c\u00d2a ch\u00dbng ta ? C6 M\u00c8t \u00b4t\u00b4 ch\u03c0y \u00c6\u2260\u00d3c qu\u2211ng \u00c6\u2260\u00cdng 100km v\u00cci l\u02d8c k\u00e4o trung b\u25canh l\u00b5 700N, ti\u2122u th\u00d9 h\u2019t 5 l\u203at x\u00aeng (kho\u2202ng 4kg). T\u203anh hi\u00f7u su\u2020t c\u00d2a \u00c6\u00c8ng c\u00a8 \u00b4t\u00b4. \u00df\u00c8ng c\u00a8 nhi\u00f7t l\u00b5 \u00c6\u00c8ng c\u00a8 trong \u00c6\u201e m\u00c8t ph\u00abn n\u00aeng l\u2260\u00d3ng c\u00d2a nhi\u2122n li\u00f7u b\ufb01 \u00c6\u00cbt ch\u220fy \u00c6\u2260\u00d3c chuy\u201dn ho\u220f th\u00b5nh c\u00a8 n\u00aeng. Hi\u00f7u su\u2020t c\u00d2a \u00c6\u00c8ng c\u00a8 nhi\u00f7t : A H= Q 99"]