202110243-TRIUMPH-STUDENT-WORKBOOK-PHYSICAL_SCIENCE-G09-PART1

Physical Science Workbook_9_P_1.pdf 1 18-10-2019 14:14:36 Name: ___________________________________ Section: ________________ Roll No.: _________ School: __________________________________

Table of Contents 1 24 1 MATTER AROUND US 59 2 MOTION 100 3 LAWS OF MOTION 145 4 REFRACTION OF LIGHT AT PLANE SURFACES 181 5 GRAVITATION 213 6 IS MATTER PURE? 259 7 ATOMS, MOLECULES AND CHEMICAL REACTIONS 292 8 FLOATING BODIES 314 9 WHAT IS INSIDE THE ATOM? PROJECT BASED QUESTIONS TABLE OF CONTENTS

1. MATTER AROUND US SESSION 1 PROPERTIES OF STATES OF MATTER 1.1 Mind Map 1.2 Terminology i. Matter – A substance that occupies space and has mass. Matter consists of various types of particles, each with mass and size. The most familiar examples of material particles are the electron, the proton and the neutron. ii. States of matter – State of matter is defined in terms of the phase transitions which indicate the change in structure and properties. Solids, liquids and gases all are made up of microscopic particles. iii. Particle – A minute portion of matter. iv. Diffusion – Diffusion is the net movement of molecules or atoms from a region of high concentration to a region of low concentration. This is also referred to as the move- ment of a substance down a concentration gradient. 1.3 Key Concepts i. Matter is made up of particles. ii. The particles of matter are very small – they are much beyond our imagination. iii. Particles of matter have space between them. iv. Particles of matter move continuously. v. Matter exists in three states i.e., solid, liquid and gas. vi. The force of attraction between the particles is maximum in solids, intermediate in liquids and minimum in gases. SESSION 1. PROPERTIES OF STATES OF MATTER 1

vii. The arrangement of particles is most ordered in case of solids, less ordered in case of liquids, while for gases there is no order i.e; particles move randomly. viii. The states of matter are interconvertible. One state of matter can be changed to another by changing temperature or pressure. 1.4 Reflection on Concepts Q1. [AS1] Explain diffusion phenomenon based on the states of matter. [Refer to TB page 9 Q1] A. Diffusion is the net movement of molecules or atoms from a region of high concentration to a region of low concentration. Rate of diffusion of gases is higher than the liquids, while the rate of diffusion of liquids is higher than solids. Examples of diffusion are as follows: Diffusion in gases – When we light the incense stick, the scent in the vapour form and smoke mixes with air and moves across the room and reach our nose. The movement of air, vapours of scent and smoke from one place to other is known as diffusion. In this case, smoke, vapour of scent and air are gases and are highly mobile. If you spray a perfume or deodorant in one corner of the room, it spreads soon to all directions. Diffusion in liquids – If we put few drop of blue or red ink or Potassium permanganate solution slowly into a glass flask containing water, we observe violet coloured chemical slowly diffusing into water causing the water to become coloured. This phenomenon illustrates diffusion of liquids in liquids. Diffusion of a solid into liquid – If we drop few crystals of potassium permanganate into a beaker containing water, we observe that the crystals of potassium permanganate gradually intermingle with water to form a pink solution. Q2. [AS1] What is a fluid? [Refer to TB page 9 Q4] A. A substance that has no fixed shape and yields easily to external pressure; a gas or (especially) a liquid is called a fluid. Example: water, blood, air. SESSION 1. PROPERTIES OF STATES OF MATTER 2

Q3. [AS1] Mention the properties of solids. [Refer to TB page 9 Q2] A. i. Solids have definite mass, shape and volume. ii. Compressibility and fluidity is not possible. iii. They have high density and inter particle forces. iv. They diffuse very slowly. v. Expansion on heating is very less. vi. They are very rigid. Q4. [AS1] Mention the properties of liquids. [Refer to TB page 9 Q3] A. i. Liquids acquire the shape of the container. ii. They have definite volume. iii. Almost negligible compressibility. iv. Less rigid. v. They diffuse fast. vi. Packing of particles is less. vii. Inter particle forces slightly weaker than in solids. Q5. [AS1] Mention the properties of gases. [Refer to TB page 9 Q5] A. i. Gases acquire the shape of the container. ii. They have indefinite volume. iii. They are highly compressible. iv. The diffuse very fast. v. Force between the particles is negligible. vi. They are loosely packed. vii. They are not rigid. viii. Fluidity is more. Q6. [AS1] Give two daily life situation where you observe the diffusion. [Refer to TB page 9 Q6] A. i. A tea bag placed in a cup of hot water will diffuse into the water. ii. Incense sticks smoke diffuses into the air. SESSION 1. PROPERTIES OF STATES OF MATTER 3

1.5 Application of Concepts Q1. [AS2] How can we smell perfume sitting several metres away from the source? [Refer to TB page 10 Q3] A. The fragrance of the perfume sprayed in one corner of the room reaches to the other corner by a process called diffusion. The particles of perfume vapours move in air for several metres. The particles of the perfume spread rapidly in all directions as they collide with air particles as they move along. Q2. [AS1] Mention works where we use compressibility in our daily life? [Refer to TB page 10 Q1] A. i. Gas cylinders - gas is compressed and stored in cylinders. ii. Shaving cream is compressed, so it comes outside as a foam. iii. Due to the compressibility only medicines in syringe infected in to our body through needle. iv. Due to the compressibility property only liquids adjust themselves in a container. Q3. [AS1] Mention the situations where we use diffusion in our day-to-day life. [Refer to TB page 10 Q2] A. i. The mixing of different gases in air is a natural process that takes place continuously. ii. Smoke coming out of factories is seen only near the mouth of chimneys. After rising high it mixes up with air and vanishes out. This happens because of diffusion or gases. iii. When salt solution kept in water this makes the whole solution salty after some times. This happens because of diffusion in liquids. Q4. [AS3] How do you prove that the speed of diffusion of ammonia is more than that of the speed of diffusion hydrochloric acid? [Refer to TB page 10 Q4] A. Procedure: i. Take a one metre long narrow glass tube. SESSION 1. PROPERTIES OF STATES OF MATTER 4

ii. Take two pieces of cotton. Soak one in hydrochloric acid solution and another in ammonia solution. iii. Insert them separately at the two ends of the tube with the help of tongs. At the same time close the ends of the glass tube with rubber cork and observe. We will observe the hydrochloric acid gives off hydrogen chloride gas and ammonia solution gives off ammonia gas. Both gases react together to form a white fumes of ammonium chloride. When the two gases reacted there was a white ring formed which is close to cotton wool with the HCl and far from the cotton wool with the NH3. Q5. [AS1] Give examples that the matter which will be available in different states. [Refer to TB page 10 Q5] A. a) Solid state: Ice, glass, rock, most metals, table sugar, frozen CO2 (dry ice), wood, butter etc. b) Liquid state: Water, alcohol, milk, mercury, vegetable oil, ethanol, bromine, blood, honey, coffee etc. c) Gaseous state: Air, helium, nitrogen, water vapour, propane, natural gas, ozone, hydrogen sulphide etc. Q6. [AS1] Draw the diagram showing the experimental arrangement to verify the speed of diffusion of two gases. [Refer to TB page 10 Q6] 1.6 Suggested Experiments Q1. [AS3] Conduct an experiment to observe the speed of diffusion of two substances. [Re- fer to TB page 10 Q1] A. Aim: To observe the speed of diffusion of two gases. Materials required: Long glass tube with scale, liquid Ammonia, Hydrochloric acid, pieces of cotton, two rubber corks and pair of tongs. SESSION 1. PROPERTIES OF STATES OF MATTER 5

Note: Teacher should take care of handling hydrochloric acid and prevent the children from touching the acid. Procedure: • Take a one metre long narrow glass tube. • Take two pieces of cotton. Soak one in hydrochloric acid solution and another in ammonia solution. • Insert them separately at the two ends of the tube with the help of tongs. At the same time close the ends of the glass tube with rubber cork and observe. Observation : The hydrochloric acid gives off hydrogen chloride gas and ammonia solution gives off ammonia gas. Both gases react together to form a white fumes of ammonium chloride. When the two gases reacted there was a white ring formed which is close to cotton wool with the HCl and far from the cotton wool with the NH3. Conclusion : One can deduce that HCl is more dense than NH3 because the NH3 travelled a farther distance than the HCl in the same period of time, hence the white ring formed closer to the cotton with the HCl (Hydrogen Chloride). Objective Questions (1) Which of the following is available in three states in our daily life? (at normal condition) (pg 10; Q 1) (A) Petrol (B) Water (C) Milk (D) Kerosene Correct Answer: B (2) Which of the following can be compressed? (pg 10; TB Q 2) (A) Iron (B) Water (C) Air (D)Wooden piece Correct Answer: C SESSION 1. PROPERTIES OF STATES OF MATTER 6

SESSION 2 WHAT IS MATTER MADE UP OF? 2.1 Mind Map 2.2 Terminology i. Compressed natural gas – Compressed natural gas or CNG, is natural gas under pressure which remains clear, odourless, and non–corrosive. ii. Sublimation – A change in which a solid on heating directly changes into vapour state without passing through the intermediate liquid phase is called sublimation. 2.3 Key Concepts i. All matters are made up of very tiny particles. ii. The space between the particles in the matter influence the speed of diffusion. iii. A change in which a solid on heating directly changes into vapour state without passing through the intermediate liquid phase is called sublimation. SESSION 2. WHAT IS MATTER MADE UP OF? 7

2.4 Higher Order Thinking Skills Q1. [AS1] We can't rejoin the broken chalk easily. Give reason. [Refer to TB page 10 Q1] A. 1) Force of attraction between the particles of the chalk is weak. 2) It is easy to break, but we can’t join. 3) To join two materials we need to let the molecules of two get near enough for the coulomb forces to start acting. Q2. [AS2] Is the space between the particles in the matter influence the speed of diffusion? Explain. [Refer to TB page 10 Q2] A. Yes. The space between the particles in the matter influence the speed of diffusion 1) Space between the particles of gaseous substance is more than solids and liquids. 2) In making of soda water, if we pass CO2 into water it diffuses fastly. 3) When we try to mix two liquids they also diffuses fastly but when compared to gas to liquid, it take more time to diffuse. 4) If we try to dissolve sugar or salt in water they will take more time to diffuse because the space between particles is very less in solid state substance. 5) So we can conclude that space between gas to liquid particles is more and take more time to diffuse and space between the two liquids particles is more so, they will diffuse speedly. 2.5 Suggested Experiments Q1. [AS3] Conduct an experiment to show the space between the particles of matter and write the report. [Refer to TB page 10 Q2] A. a) take a graduated beaker and fill it with some water and mark the water level. b) Add some salt and stir it thoroughly with a glass rod. SESSION 2. WHAT IS MATTER MADE UP OF? 8

c) When all the salt has dissolved, we get a salt solution. d) Observe the level of salt solution in the beaker. We will find that the level of salt solution in the beaker is at the same mark where water level was initially in the beaker. e) From this activity, we can conclude that both the solid and liquid particles have some space between them and the solid particles enter into the space between the liquid particles when we dissolves them in liquids. 2.6 Suggested Projects Q1. [AS4] Make a model to explain the structure of particles in solids, liquids and gases. [Refer to TB page 10 Q1] A. Suggestions for making a model. i. Take three rectangular flat plates of the same size. ii. Mark the plates as A, B and C. iii. Arrange marbles in plate (A) such that the distance between each of them on any side is just 1 mm. iv. Arrange marbles in plate (B) such that the distance between each of them on any side is just 3 mm. v. Arrange marbles in plate (C) such that the distance between each of them on any side is just 5 mm. vi. Plate (A) represents the arrangement of particles in solids. Plate (B) represents arrangement of particles in liquids and plate (C) represents the particles in gases. SESSION 2. WHAT IS MATTER MADE UP OF? 9

Q2. [AS4] What are the factors influencing diffusion, whether the arrangement of atoms in the substance that diffuse or the arrangement of atoms of the medium in which the substance is kept? [Refer to TB page 10 Q2] A. i. Diffusion depends on both material that is diffusing and the material it is diffusing through. ii. At certain temperature, all particles have the same average energy. iii. This means that lighter atoms, such as hydrogen, carbon, oxygen and nitrogen travel faster and are more mobile than larger atoms such as copper or iron. iv. Materials made of these lighter atoms diffuse faster than heavier materials. Q3. [AS4] Some solids diffuse in liquids but not in gasses, some solids diffuse in gasses but not in liquids. Why? [Refer to TB page 10 Q3] A. Some solids diffuse in liquids but not in gasses. We take sugar and add it to water it will diffuse in it. But if we keep it in air it won’t diffuse. Here diffusion is not going in solids when we keep in air because, the particles in a solid can only vibrate on the spot, rather than being able to move from place to place. Some solids diffuse in gasses because they are sublimators. They won’t dissolve in liquids. Objective Questions (1) In which of the following substance speed of diffusion is more ( Pg 10; TB Q 3) (A) Smell of Petrol (B) Smell from flowers (C)Smell from Napthaline balls (D)Gas leaked from gas cylinder Correct Answer: D SESSION 2. WHAT IS MATTER MADE UP OF? 10

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Match the following. [] Column B i. a. Gases [(Session 1.1)] Column A CNG ii. Gases [ ] b. Definite shape and fixed volume iii. Solids [ ] c. High compressibility iv. Rate of diffusion is higher in [ ] d. Fixed volume and no definite shape v. Liquids [ ] e. Compressed Natural gas 2. State true or false. [] [Refer to Session 1.2 ] [] [] (i) Rate of diffusion in liquids is highest. (ii) Solids have largest inter–particle space. (iii) Gases have strongest inter–particle forces. 3. Fill in the blanks. [Refer to Session 1.2 ] CHAPTER 1. MATTER AROUND US 11

(i) Matter is made up of small . (ii) Particles in solids are packed. (iii) Particles of matter have between them. (iv) Particles in gases are packed. (v) Force of attraction between particles is in solids. (vi) In gases, particles move_________________. (vii) Diffusion is possible only when particles of matter _____________ continuously. Short Answer Type Questions 4. Answer the following questions in 3-4 sentences. (i) [(Session 1.1)] What is diffusion? (ii) [(Session 1.1)] Give examples for diffusion in both liquids and gases. CHAPTER 1. MATTER AROUND US 12

5. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] Why is the rate of diffusion high in gases? Long Answer Type Questions 6. Answer the following questions in 6-8 sentences. (i) [(Session 1.1)] Describe the following properties. Compare these properties of solid, liquid and gas. a. Compressibility b. Shape and volume CHAPTER 1. MATTER AROUND US 13

AS2-Asking questions and making hypothesis Short Answer Type Questions 7. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] Ice floats on water rather than sinking. What questions would you ask to understand this phenomenon? (ii) [(Session 1.2)] Rani says there is something in her hand that doesn’t have a fixed shape but has a fixed volume. Think and tell the state of matter of the substance that is there in her hand. Give reasons to substantiate this hypothesis. Long Answer Type Questions 8. Answer the following questions in 6-8 sentences. (i) [(Session 1.1)] The fragrance of the unlit agarbati does not spread in the entire room. But a lit agarbati’s fragrance spreads in the entire room. Why do you think this hap- pens? What questions would you ask to understand this phenomenon? CHAPTER 1. MATTER AROUND US 14

AS3-Experimentation and field investigation Short Answer Type Questions 9. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] How is it possible for two small crystals of potassium permanganate to colour a large volume of water? CHAPTER 1. MATTER AROUND US 15

Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 1.2)] What property of liquid will you observe by doing an experiment using a flask of water and Potassium permanganate solution? Write the experiment. CHAPTER 1. MATTER AROUND US 16

AS4-Information skills and projects Very Short Answer Type Questions 11. Answer the following questions in one sentence. [Refer to Session 1.1 ] (i) Complete the table. Property Solid Liquid Gas Shape Fixed Fixed Volume (ii) Complete the table. 17 CHAPTER 1. MATTER AROUND US

Property Gas Liquid Solid Compressibility Intermediate Very less Diffusion AS5-Communication through drawing and model making Long Answer Type Questions 12. Answer the following question. (i) [(Session 1.1)] Draw a diagram to explain how the particles are arranged in a solid, liquid and gas. CHAPTER 1. MATTER AROUND US 18

AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 13. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] Ram was returning home from school. As soon as he reached the front door of his house, he knew that his mother was cooking his favourite dish. Appreciate how you think he got to know his mother was making his favourite dish. Long Answer Type Questions 14. Answer the following questions in 6-8 sentences. (i) [(Session 1.2)] Which property of gases is appreciable in case of filling LPG in the cylinder? Explain. CHAPTER 1. MATTER AROUND US 19

AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 15. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] Can you give one example where solid converts directly into gaseous state? CHAPTER 1. MATTER AROUND US 20

Objective Questions AS1-Conceptual Understanding 16. Choose the correct answer. (i) Matter exists in states. (A) 2 (B) 3 (C) 1 (D) 5 (ii) Shape of liquids depends on (B) density of liquids (A) volume of container (C)shape of container (D) colour (iii) Which of the below occupies more intermolecular space? (A) Gases (B) Liquids (C) Solids (D)All the above (iv) Which of the below has high compressibility? (A) Solids (B) Liquids (C) Gases (D)All the above (v) Which of the below has no fixed shape but fixed volume? (A) Solids (B) Liquids (C) Gases (D)Both B and C (vi) The arrangement of particles in the solids is best denoted by: (A) Space between the particles is highest (B) Space between the particles is least CHAPTER 1. MATTER AROUND US 21

(C)Space between the particles is medium (D)There is no space between the particles (vii) The forces of attraction between the particles of gases are (A) not present (B) highest (C) least (D) medium (viii) Forces of attraction between particle are medium in . (A) liquid (B) solid (C) gases (D) none (ix) A change in which a solid on heating directly changes into vapour state is called . (A) sublimation (B) oxidation (C) evaporation (D) condensation (x) When a substance changes its state there is no change in . (A) mass (B) density (C) volume (D) none CHAPTER 1. MATTER AROUND US 22

AS7-Application to daily life, concern to bio diversity 17. Choose the correct answer. (i) When sugar is dissolved in water, there is no increase in the volume. This shows (A) the sugar has no volume at all (B) sugar when dissolved in water, looses its basic property and disappears (C)water can dissolve sugar (D)there is still presence of space between the particles of liquid CHAPTER 1. MATTER AROUND US 23

SESSION 1 2. MOTION 1.1 Mind Map MOTION, DISTANCE AND DISPLACEMENT SESSION 1. MOTION, DISTANCE AND DISPLACEMENT 24

1.2 Terminology i. Distance –The length of the actual path traversed by an object. ii. Displacement –The length of the straight line path between the initial and final posi- tions of the object iii. Vector – Quantities that are expressed with both magnitude and direction. iv. Scalar – Quantities that can be expressed only using magnitude. v. Relative – Considered in relation or in proportion to something else. 1.3 Key Concepts i. The change of position of an object with respect to time is called motion. ii. Motion is relative. It depends on the observer. iii. It can be described in terms of distance travelled or on the displacement. 1.4 Suggested Projects Q1. [AS2] Suppose that the three balls shown in figure start simultaneously from the top of the hills. Which one reaches the bottom first? Explain. [Refer to TB page 30 Q2] A. Among all the three cases, in the second and third hill the ball takes a curved path and covers a large distance. Since, the distance in the first hill is the least, the ball in the first case will reach the bottom first. SESSION 1. MOTION, DISTANCE AND DISPLACEMENT 25

SESSION 2 SPEED AND VELOCITY 2.1 Mind Map 2.2 Terminology i. Average speed –The ratio of total distance covered to total time taken. ii. Average velocity – The ratio of total displacement covered to total time taken. iii. Instantaneous speed – Speed of any moving body at any instance of time. iv. Velocity – Displacement per unit time. v. Acceleration –Velocity per unit time. 2.3 Key Concepts i. Average speed is distance covered in unit time and average velocity is displacement covered in unit time in a particular direction. ii. Velocity has both magnitude and direction and so it is a vector. iii. Speed at a particular instant is called instantaneous speed which gives an idea of how fast the position of the body is changing. SESSION 2. SPEED AND VELOCITY 26

2.4 Reflection on Concepts Q1. [AS1] Distinguish between speed and velocity. [Refer to TB page 28 Q1] A. Speed Velocity 1. The distance 1. Velocity is the displacement covered per unit per unit time. time is called speed of an object. 2. Speed has 2. Velocity has both magnitude magnitude but no and direction. direction. 3. Speed is a scalar. 3. Velocity is a vector. 4. Total Distance = 4. Displacement = Average Average speed × velocity × Time taken Time taken Q2. [AS1] Are average speed and average velocity same? If not explain why. [Refer to TB page 28 Q4] A. Average velocity is displacement in a specified direction per unit time. But Average speed is total distance covered in a time. Q3. [AS1] How do you measure instantaneous speed? [Refer to TB page 28 Q5] A. Using a speedometer Q4. [AS1] Explain acceleration with an example. [Refer to TB page 28 Q6] A. The rate of change of velocity of an object is called acceleration. We experience acceleration many times in our day to day activities. For example, if we are travelling in a bus or a car, when the driver presses the accelerator, the passengers sitting in the bus experience acceleration. Our bodies press against the seat due to the acceleration. Q5. [AS1] What do you mean by acceleration? [Refer to TB page 28 Q7] A. The rate of change of velocity of an object is called acceleration. SESSION 2. SPEED AND VELOCITY 27

2.5 Application of Concepts Q1. [AS1] In the above figure given distance v/s time graphs showing motion of two cars A and B are given. Which car moves faster? [Refer to TB page 29 Q1] A. 1. If we draw perpendiculars to X and Y axes from A and B respectively, we can observe that A covers large distance (s1) within a short time (t 1). 2. Find the slopes of the lines OA and OB at any instant. Slope of OA is high. Hence Car A moves faster. Q2. [AS1] A train of length 50 m is moving with a constant speed of 10 m/s. Calculate the time taken by the train to cross an electric pole and a bridge of length 250 m. [Refer to TB page 29 Q3] A. Distance = Speed × T ime Note: A train has to travel its own length in order to cross an electric pole, railway signal, a tree, a kilometre stone or stationary man. SESSION 2. SPEED AND VELOCITY 28

Distance to be travelled = Length of the train = 50 m Speed of train = 10 m/s Time taken to cross the electric pole = 50m = 5s 10m/s To cross a bridge/ platform/ another train, a train has to travel the total length of both the bridge as well as the train itself. Distance to be travelled by the train = length of train + length of bridge Length of train = 50 m Length of bridge = 250 m Distance to be travelled = 50 m + 250 m = 300 m Distance = 300m Time taken by train to cross the bridge = Distance = 300/10 = 30s Speed Q3. [AS7] What is the average speed of a cheetah that sprints 100 m in 4 s? How if it sprints 50 m in 2 s? [Refer to TB page 29 Q6] A. Total distance = 100 m Time taken = 4 s Average speed of cheetah= 100/4 = 25m/s If it sprints at 50 m in 2 s Total distance = 50, Average speed= T otal Distance T ime T aken Time taken = 2 s Average speed of cheetah= 50/2 = 25m/s SESSION 2. SPEED AND VELOCITY 29

Q4. [AS7] A car travels at a speed of 80 km/h during the first half of its running time and at 40 km/h during the other half. Find the average speed of the car. [Refer to TB page 29 Q7] A. Let us say that the car has travelled for t hours. Distance travelled in first half of time = velocity in first half x t = 80t km 2 2 Distance travelled in second half of time= velocity in second half × t = 40t km 2 2 Therefore, average speed = Total distance travelled = 80t + 40t = 60 km/h Total time taken 2 2 t 2.6 Higher Order Thinking Skills Q1. [AS2] When the velocity is constant, can the average velocity over any time interval differ from instantaneous velocity at any instant? If so, give an example; if not, explain why. [Refer to TB page 29 Q1] A. When the velocity is constant, the average velocity over any time interval does not differ from instantaneous velocity at any instant. Example: If we draw the velocity–time graph for a car moving at an average velocity of 50 km/h, we get a straight line graph parallel to x–axis and the height of the straight line will not change with time. It will be a straight line parallel to the x–axis. Q2. [AS5] You may have heard the story of the race between the rabbit and tortoise. They started from same point simultaneously with constant speeds. During the journey, rabbit took rest somewhere along the way for a while. But the tortoise moved steadily with lesser speed and reached the finishing point before the rabbit. The rabbit awoke and ran, but the tortoise reached the goal even before the rabbit finished the race and won the race. Draw distance v/s time graph for this story. [Refer to TB page 29 Q2] SESSION 2. SPEED AND VELOCITY 30

A. 2.7 Suggested Projects Q1. [AS4] Calculate the average speeds of students of your class who have participated in 100 metres and 200 metres running race. Write a report. (Refer to TB page 30 Q 1) A. Students’ activity. Objective Questions (1) The distance travelled by an object in a specified direction is ( Pg 30; TB Q 1) (A) Speed (B) Displacement (C) Velocity (D) Acceleration Correct Answer: C SESSION 2. SPEED AND VELOCITY 31

SESSION 3 UNIFORM AND NON-UNIFORM MOTION 3.1 Mind Map SESSION 3. UNIFORM AND NON-UNIFORM MOTION 32

3.2 Terminology i. Acceleration – Rate of change of velocity. ii. Rectilinear motion – Motion along a straight line. 3.3 Key Concepts i. When the velocity is constant we say the motion is uniform. ii. If the velocity of a moving body changes, the body is said to have acceleration. iii. Rate of change of velocity is called acceleration. iv. If the acceleration is constant, the motion is said to have uniform acceleration. v. Negative acceleration is called deceleration. vi. Equations of motion are (i) v = u + at, (ii) s = ut + 1 at2 and (iii) v2–u2 = 2as 2 3.4 Reflection on Concepts Q1. [AS1] Briefly explain about constant acceleration? [Refer to TB page 28 Q2] A. Constant acceleration means that the object accelerates uniformly over equal intervals of time however small the time intervals may be. Q2. [AS1] How can you say that a body is in motion ? is it a common property? [Refer to TB page 28 Q3] SESSION 3. UNIFORM AND NON-UNIFORM MOTION 33

A. A body is said to be in motion when its position is changing continuously with time relative to an observer. Motion is relative to observer. 3.5 Application of Concepts Q1. [AS1] A body leaving a certain point “O” moves with a constant acceleration. At the end of the 5 th second its velocity is 1.5m/s. At the end of the sixth second the body stops and then begins to move backwards. Find the distance traversed by the body before it stops. Determine the velocity with which the body returns to point “O”. [Refer to TB page 29 Q2] A. Let v = 1.5m/s; t1 = 5s; t2 = 6s From v = u + at1, we have 1.5 = u + a(5) For the sixth second, using v = u + at, we have 0 = 1.5 + a(1) or, a = −1.5m/s2 Therefore,u = 1.5 − 5(−1.5) = 1.5 + 7.5 = 9m/s Now, distance from 'O' to stop, i.e. 0 to 6 seconds, S1 = v2−u2 = 0−81 = 81 = 27m 2a 2(−1.5) 3 For motion in reverse with the same acceleration, the velocity of the body when it reaches 'O' at the same acceleration, is the same as u, i.e. 9 m/s, in the opposite di- rection. Q2. [AS5] Draw the distance v/s time graph when the speed of the body increases uniformly. [Refer to TB page 29 Q4] A. SESSION 3. UNIFORM AND NON-UNIFORM MOTION 34

Q3. [AS5] Draw the distance–time graph when its speed decreases uniformly. [Refer to TB page 29 Q5] A. Q4. [AS7] A particle covers 10 m in first 5 s and 10 m in next 3 s. Assuming constant acceleration find initial speed, acceleration and distance covered in next 2 s. [Refer to TB page 29 Q8] A. The particle covered 10 m in first 5 s. That is s5 = 10m; t = 5s The particle covered 10 m in the next 3 s. That is s8 − s5 = 10m Let initial velocity be ‘u’ m/s, and acceleration be ‘a’ m/s2 Then, s5 = u(5) + 1 a(5)2 2 i.e.10 = 5u + 25 a 2 Similarly, s8 = u(8) + 1 a(8)2 2 s8 = 8u + 32a Therefore, s8 − s5 = 8u + 32a–10 = 10 i.e.8u + 32a = 20 or, 2u + 8a = 5 or, u = 5−8a 2 SESSION 3. UNIFORM AND NON-UNIFORM MOTION 35

Substituting this in the equation for s 5 , we get 10 = 5 5−8a + (25/2) a 2 10 = 5 5−8a + 25 a 2 2 10 = 25 − 20a + 25 a 2 2 10 − 25 = − 15 a 2 2 − 5 = − 15 a 2 2 ⇒ a = 1 m/s2 3 Therefore, u = 5−8a = 5−8 1 = 7 m/s 2 2 3 6 Distance covered in next two seconds, s = s10 – s8 s= 7 10 + 1 1 102 − 20 6 2 3 s = 70 + 100 − 20 = 170 − 20 = 50 = 8.33m 6 6 6 6 3.6 Higher Order Thinking Skills Q1. [AS7] A man is 48 m behind a bus which is at rest. The bus starts accelerating at the rate of 1 m/s2. At the same time the man starts running with uniform velocity of 10 m/s. What is the minimum time in which the man catches the bus? [Refer to TB page 29 Q3] A. a = 1 m/s2 SESSION 3. UNIFORM AND NON-UNIFORM MOTION 36

s = ut + 1at2 2 n = 0(t) + 1(1)t2 2 ∴ n = t2 2 48 + n = 10t 48 + t2 = 10t 2 96 + t2 = 20t t2 − 20t + 96 = 0 or, t = 8s, 12s Thus, minimum time = 8 seconds 3.7 Suggested Experiments Q1. [AS3] Conduct an experiment to find acceleration and velocity of an object moving on an inclined plane and write a report? [Refer to TB page 30 Q1] A. Aim: To find the acceleration and velocity of an object moving on an inclined track. Materials required: Glass marbles, book, digital clock, long plastic tubes and steel plate. Procedure: • Take a long plastic tube of length nearly 200 cm and cut it in half along the length of the tube. • Use these tube parts as tracks. • Mark the readings in cm along the track. • Place the one end of the tube on a book and the other end on the floor, as shown in given figure– SESSION 3. UNIFORM AND NON-UNIFORM MOTION 37

• Keep a steel plate on the floor at the bottom of the track. Consider the reading at the bottom of the track to be zero. • Take a marble having adequate size to travel in the track freely. • Now release the marble freely from a certain distance say 40 cm. • Start the digital clock when the marble is released. • It moves down on the track and strikes the steel plate. • Stop the digital clock when a sound is produced. • Repeat the same experiment for the same distance 2 to 3 times and note the values of times in the given table . • Repeat the same experiment for various distances. • Find average time and 2S /T2for every trail. Distance Time Average 2S S (cm) T(s) Time T2 T1 T2 T T3 SESSION 3. UNIFORM AND NON-UNIFORM MOTION 38

Objective Questions (1) If an object is moving with constant velocity then the motion is (Pg 30; TB Q 2) (A) Motion with Non uniform Acceleration (B) Motion with Uniform Acceleration (C)Uniform motion (D)Non uniform motion Correct Answer: C (2) If there is change in the velocity of the object then the state of object with respect to motion is(Pg 30; TB Q3) (A) State of Constant Speed (B) State of constant velocity (C) State of Uniform Motion (D) State of Non uniform Motion Correct Answer: D (3) If the acceleration of a moving object is constant then the motion is said to be (Pg 30; TB Q 4) (A) Motion with Constant Speed (B) Motion with Uniform Acceleration (C)Motion with Uniform Velocity (D) Motion with Non Uniform Acceleration Correct Answer: B —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Answer the following questions in one sentence. [Refer to Session 2.3 ] (i) State which of the following is uniform motion and which is a non–uniform motion. a. A car going on a straight level road with steady speed. ___________________. b. A cooling fan running. ________________________________. c. A roller coaster ride. _________________________________. d. A motorist riding on a hill. _____________________________. e. Planets revolving around sun. __________________________. CHAPTER 2. MOTION 39

2. Fill in the blanks. [Refer to Session 2.3 ] (i) The motion is uniform when the velocity is . (ii) The body has when the velocity of body changes. (iii) The motion is said to be accelerated motion if acceleration is constant. (iv) In a circular path changes but remains constant. (v) SI unit of acceleration is . 3. State true or false. [Refer to Session 2.2 ] (i) The distance covered and displacement are time dependent quantities. ] [ (ii) In rectilinear motion the distance and magnitude of displacement become unequal. [] (iii) Motion is relative and it is dependent on the observer. [] 4. Fill in the blanks. [Refer to Session 2.2 ] (i) Distance travelled by a body in unit time is known as . (ii) Change in velocity of a body per unit time is known as __________________ . (iii) Speed at any instant is . (iv) Displacement of body per unit time is . (v) Equation for average speed is _____________ or _____________________ . CHAPTER 2. MOTION 40

5. Match the following. [] Column B [(Session 2.1)] a. Total distance/time taken Column A b. Scalar c. Motion i. Displacement d. Displacement/time taken ii. A body’s position is changing [ ] e. Vector iii. Distance [] iv. Average speed [] v. Average velocity [] 6. Fill in the blanks. . [Refer to Session 2.1 ] segment. (i) Motion of an object depends on . (ii) A vector can be represented as a directed . (iii) The SI unit of distance and displacement is (iv) Velocity is speed in specified (v) Physical quantity which does not require any direction is . Short Answer Type Questions 7. Answer the following questions in 3-4 sentences. (i) [(Session 2.2)] Which device(s) on a car can be used to change: a. Its speed? b. Its velocity but not it’s speed? CHAPTER 2. MOTION 41

(ii) [(Session 2.2)] Can the direction of velocity of an object reverse when its acceleration is constant? If so give an example; if not, explain why? 8. Answer the following questions in 3-4 sentences. (i) [(Session 2.1)] Define the terms scalar and vector. (ii) [(Session 2.1)] Define motion, average speed and average velocity. Give equations for each of them. CHAPTER 2. MOTION 42

Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 2.3)] Write and derive the three equations of motion. CHAPTER 2. MOTION 43

(ii) [(Session 2.3)] A car, initially at rest, picks up a velocity of 72 kmh-1 in 1/4th minutes. Calculate (a) Acceleration (b) Distance covered by car. CHAPTER 2. MOTION 44

10. Answer the following questions in 6-8 sentences. (i) [(Session 2.2)] From the diagram, calculate: (a) De–acceleration in region AB 45 (b) Acceleration in the region BC (c) Total distance travelled in the region ABC (d) Average velocity between 10s and 30s CHAPTER 2. MOTION

(ii) [(Session 2.2)] The velocity of a car changes from 18 Kmh-1 to 72 Kmh-1 in 30 s. Calculate (A) change in velocity in ms-1 (B) acceleration in (a) Km h-2 (b) ms-2 CHAPTER 2. MOTION 46

11. Answer the following questions in 6-8 sentences. (i) [(Session 2.1)] An aeroplane touches the ground at a speed of 225 m/s and stops after 2 minutes.Calculate – (a) Acceleration (b) Length of runway (ii) [(Session 2.1)] From the displacement–time graph given in the figure, calculate: (A) Velocity between 0 and 4s (B) Velocity between 4s and 6s (C) Velocity between 6s and 9s (D) Average velocity from: (a) 0 - 4s (b) 0 - 6s (c) 0 - 9s CHAPTER 2. MOTION 47

CHAPTER 2. MOTION 48