Big Book of Knowledge

Making molecules Larger than life Atoms link up to make molecules. These long, thin wax Two atoms of hydrogen join molecules are shown about together to make one molecule 3 million times larger than of hydrogen gas. they are in real life. The tiny blue dots are atoms The molecules in that have joined together to a cool solid do not make up the wax molecules. move around very fast. If a solid is Sugar heated, the molecules Crystal clear move around faster Grains of sugar are and faster. solid crystals. Their atoms are close together and arranged in a regular pattern called a lattice. Many solids that look smooth actually have a crystal structure, like these vitamin C tablets. Vitamin C Vitamin crystals, seen C tablets through a microscope. A shell is hard There are strong Graphite and brittle. links between the and diamond molecules in a Graphite is soft and is solid.This means used in pencils, and that solids have diamond is the hardest a fixed shape. solid in the world. But A spider’s web is diamond and graphite light and strong. have a lot in common! They are two different forms of carbon. This means they have the same molecules, but they are arranged in different ways. 399

LIQUIDS Syrup Car oil flows flows slowly. fairly well. If you spread some butter on hot toast, Ink flows the butter melts. When a solid gets very easily. hot enough to melt, it turns into a liquid. Liquids behave differently than solids. The Sticky spoonful heat that melts a solid breaks Some liquids flow down some of the strong links much more easily between molecules, so that the than others. Liquids that are “viscous” do not flow well. molecules can move around more freely. A Molecules in a liquid liquid flows because its molecules can’t hold These children are behaving together strongly enough to form a solid shape. like molecules in a liquid. Fair shares? Liquid levels Who has more milk to Liquids flow to fill containers of drink? It may not look any shape or size. The surface of a like it, but these glasses liquid always stays level however hold the same amount. much you may tilt the container. Containers of different shapes can hold the same volume, or amount, of liquid. 400

Too hot On the boil to handle? When a liquid is heated to a Ice creams melt certain temperature, it turns very easily, but into a gas. This temperature is not all solids called the boiling point. Different have such low liquids have different boiling melting points. points. The water in this pan Some only melt if boils at 212°F (100°C). they are heated to very high temperatures. The steel in this factory melts at 2,732°F (1,500°C). In a liquid, the Moving molecules can get molecules are separate into all the corners of a from each other. container.This is why liquids take up the shape of the container that holds them. Molecules in a liquid are not Molecules in a liquid Bad mixers arranged in a regular pattern, move around faster than Some liquids do not so they can move around freely. molecules in a solid. mix at all. Oil does not On the surface Good mixers dissolve in water. Molecules near the surface of a liquid Cranberry juice mixes pull toward each other. A drop keeps well with water. It its shape because of this surface dissolves completely. tension. If some dishwashing liquid is added to a water drop, the surface tension is made weaker, so the drop spreads out. 401

GASES Gases are all around us and can’t usually be seen or felt, but some can be smelled. Lighter than air All smells are molecules of gas mixed in When a gas gets hot, it takes up the air. If you smell some tasty soup, you more room and gets lighter. A hot-air are actually sniffing in molecules of the soup. balloon rises up in the air because the When you heat a liquid, it turns into a gas. air inside it is hot, and much lighter The heat makes the molecules in the liquid than the air outside. move around faster and faster. The gas molecules fly off in all directions, spreading through the air. Molecules in a gas Each child is acting like a molecule in a gas. Look how they are bumping into each other. Dancing on air There are no links When a shaft of light shines through between any of the a gap in the trees, specks of dust look molecules in a gas. like they are dancing in the sunlight. What is really happening is that the Carbon dioxide In the air Other gases There are a number molecules in the air of different gases in currents move around, Oxygen the air we breathe. flicking the dust 78 percent of air is in all directions. Nitrogen nitrogen gas. Oxygen As a gas spreads, the makes up 21 percent. molecules get farther Carbon dioxide and and farther apart. a variety of other Gases will always gases make up just spread to fit the one percent of the space they are in. gases in the air. 402

Pumping air High pressure It is easy to squash Air presses on everything together, or compress, on Earth. You can see gas molecules. When air pressure at work. If you pump up a tire, you you suck juice out of a compress air molecules carton, the carton into a small space. The buckles. This is more air molecules you because the air pressure pump in, the more they pushing on the carton is push against the inside of greater than the air the tire. The tire gets pressure inside the carton. harder because pressure increases inside it. Molecules in a gas move very quickly, darting around in all directions. Night and day Out of breath Plants help keep the balance of gases in the Gases can dissolve in liquids, and oxygen air. Night and day, they take in oxygen and from the air dissolves in water. Fish need “breathe out” carbon dioxide, as we do. But oxygen to breathe, so they use the oxygen in by day, they also take in large amounts of water to survive under water. Humans also carbon dioxide—which they need to make breathe oxygen, but unlike fish, we can’t breathe under water without a supply of their food and give off oxygen. compressed air. 403

ENERGY Jumping jack Energy is needed for life, and When the lid is closed, for every single movement the puppet’s spring is in the whole universe. When coiled up, ready to push you have run a race, you may feel the puppet out of the that you have used up all your energy. box. We say the spring But your energy has not been lost, it has has potential energy. changed into different kinds of energy: When you open the lid, movement and heat. When work is done, energy is the spring’s potential never lost, but it changes into other kinds of energy. energy turns into Movement and heat energy are just two of the movement energy. many different kinds of energy. Energy changes Eating energy We can’t make energy, or We get our energy from destroy it. Instead, energy food, and we need to eat can change from one kind plants, or animals that to another. This toy robot have eaten plants, to stay shows how energy may alive. Plants get energy not stay in one form to grow from sunlight, so our energy really for very long! comes from the sun. Sun power Living things that grew millions of years ago were buried under rock, where they slowly turned into coal, oil, and gas. Energy from these fuels comes from the sun, shining long ago. 404

1. When the robot is switched on, chemical energy stored in the batteries turns into electrical energy. Batteries 2. As the robot moves, electrical energy turns into kinetic energy, which is another name for movement energy. Running out of energy Most machines need energy to work. The energy from oil, coal, and gas is in danger of running out altogether. Once these fuels, called fossil fuels, have been used up, we will never be able to replace them. 3. The flashing lights show that electrical energy has been changed into light energy. 4. The robot makes Everlasting energy Splitting the atom a noise as it moves. These solar collectors store the sun’s heat and Neutrons are tiny Electrical energy has use it to make electricity. Energy from the wind particles inside an atom. been turned into and waves also provides power. Scientists are If a uranium atom takes sound energy. trying to find cheaper ways of capturing the in one extra neutron, it 5. The robot gets warm. endless supply of natural energy. splits, releasing a huge Movement energy has amount of energy. changed into heat energy. Nuclear energy produces radioactive waste, which has to be handled and disposed of very carefully. 405

HEAT The sun’s rays can make you very hot. The way heat rays move through air is called radiation. You feel warm because the radiation makes the molecules in your skin move around faster than usual. Heat comes from molecules moving around. It moves through solids by conduction—the molecules in a solid vibrate, bumping the heat along. Heat travels through air and liquids in Heat moves along the a circular movement called convection. wooden spoon by conduction. The spoon takes a long time to get hot because wood is not a Snug as a bug? good conductor of heat. Heat doesn’t travel easily through air, so materials that trap air keep you warm. This polar explorer is wearing clothes made of materials that insulate his body. This means they keep his body heat close to his body, where he needs it. Tricky fingers If you dip one finger in hot water and another in cold, the hot water will feel hot and the cold water will feel cold. If you then dip both fingers in lukewarm water, your “hot” finger is tricked into finding the water cold, and your “cold” finger finds the water hot. 406

Good conductors If you heat a solid, its molecules jostle around, passing the heat from molecule to molecule. Just as a whisper moves along a line of children, so the moving molecules pass, or conduct, the heat from one end of the solid to the other. Building bridges When most solids are heated, they get As the water reaches bigger, or expand. This is because the its boiling point, it heat speeds up the molecules, and they evaporates into steam. get farther and farther apart as they When the water near move. Bridges are built with small gaps the heat source gets hot, between the sections of the roadway, it rises up toward so there is room for them to expand the surface. The cooler water near the on a hot day. The flames surface will sink to the are a direct bottom of the pan, where it source of heat. is then warmed up by the heat source. Familiar temperatures 212ºF (100ºC) Water boils 140ºF (60ºC) Cup of coffee Metal is a good 98.6ºF (37ºC) conductor of heat. Body temperature 86ºF (30ºC) Hot summer day 50ºF (10ºC) Cold drink 32ºF (0ºC) Water freezes

LIGHT Hot stuff You may need to wear Most light comes sunglasses on a sunny day, from hot objects. because the bright light A very hot object hurts your eyes. It is dangerous to look straight makes a very at the sun. The sun’s light is not just bright light. The blinding, it also travels to us very fast. sun is white hot, In just one second, light travels and sunlight is the 186,000 miles (300,000 kilometers). brightest natural If a straight beam of light has to pass through obstacles such as light we have. convex and concave lenses, it changes direction. Concave lenses This beam of light This is called refraction. curve inward in comes from a flashlight. the middle. A flashlight is a man- made light source. Retina Pupil Light bends outward when it passes through a concave lens. Optic nerve Lens Convex lenses bulge How we see light in the middle. Light enters your eye through your Light for life pupil. It passes through a lens, which Plants always grow focuses the object you are looking at toward the light, even onto the retina. Millions of tiny cells if, like this plant, they inside the retina turn this upside-down have to grow around image into electrical messages. The corners to reach it! optic nerve carries these messages to Light is very important your brain, which “sees” the image the for life. Plants need right way up. light to grow, and we need to eat plants, or animals that eat plants, to stay alive.

When a beam of light passes through a prism, the colors split apart because each wavelength is bent a different amount. The big bang! Over the rainbow Light travels faster than sound. Drops of rain act like tiny prisms. When fireworks explode high in When light passes through the sky, you see the lights before raindrops, the colors of light are you hear the loud bang. Light split up to form a rainbow. reaches your eyes more quickly Light travels in than sound reaches your ears. tiny waves. Light has a mixture of different A prism is a wavelengths. solid, triangle- shaped piece of glass or plastic. When light is reflected, the beams of light bounce off When light passes the mirror at the through a convex lens, same angle as it is bent, or refracted, they hit it. inward. When light hits an object Busy line that it can’t travel through, When you talk on the telephone, your voice is turned into laser light such as this mirror, a shadow signals and sent down very thin forms behind the object fiber glass tubes called optical where the light can’t fibers. Up to 150,000 different reach. conversations can be sent down just one of these optical fibers.

COLOR Imagine waking up in a world without color. There would be no beautiful paintings or rainbows to look at, and no bright shoes or clothes to wear. At night when you switch off the light, all the bright colors around you Color cones suddenly disappear. This is The inside of the back of your eye looks like this through a because you cannot see the color microscope.You have cells in the of an object without light. White light can be back of your eyes called cones, split into all the colors of the rainbow—shades which send messages to your brain about the colors you see. of red, orange, yellow, green, blue, indigo, and violet. When all these colors are mixed back together, they make white light again. Seeing in color If you don’t have all the different types of cones in your eyes, you may find it hard to tell some colors apart. A color-blind person may not be able to see the number on this color blindness test. White is the only color that can’t be made by mixing together the primary colors of paint. Seeing red We see things because light bounces off them. Light is Light mixing actually a mixture of all the The colors of light behave colors of the rainbow. When differently than paint colors. light hits these shoes, all the When red, green, and blue colors sink in, except the red light are mixed together, color that is reflected back they make white light. When the same colors of paint are to your eyes. mixed, it makes a dark color. 410

Paint mixing Blue, yellow, and You can make new colors red are the primary by mixing the primary colors of paint. colors of paint together. Red and yellow mix to make orange. Blue and Tasty morsels red mix to Which of these dinners make purple. do you prefer? Both Different shades meals would taste the can be made by same, but the food adding more of coloring in one puts you one color than off before you start. another. Color can change our feelings about things, especially food. Blue and yellow mix to make green. Warning colors Colors are often used as a warning. This moth is poisonous, and its bright wings warn hungry birds to leave it alone. We also use colors to warn us of danger. A red traffic light tells us to stop, but a green traffic light means that it is safe to go. 411

SOUND Astronauts talk to each other by radio because their voices can’t Deafening decibels travel through empty space. The loudness of sounds Sound travels in waves. When is measured in decibels. these waves move through air, When airplanes land, they the air molecules move quickly, reach a very high number or vibrate. If there are no air of decibels.This ground molecules, no sound is made, because there is nothing controller is wearing to vibrate. When you shout, the vocal cords in your ear protectors to prevent throat vibrate. These vibrations pass through your being deafened by mouth into the air, making the air itself vibrate. the noise. Your ear picks up the vibrations and you can hear them as sound. The bottle tops clink together when the jingling stick is shaken. Wailing whales Lentils inside Whales communicate under water over the shaker huge distances. The sound of a great make a soft, whale may travel hundreds of miles rattling sound. under water. Sound travels faster and Strings vibrate as farther through liquids and solids the instrument is than through air. This is because plucked.The tighter molecules in liquids and solids the string, the are more tightly packed. higher the note. 412

Seeing sounds Bouncing sound You can show that sound This pregnant woman can see her baby vibrations exist by hitting before it is born because of sound. High- a tray next to a drum frequency sound waves are reflected as sprinkled with rice. The they reach the baby, making an image rice bounces up and on the computer screen. down with the vibrations that the sound makes. Hitting a tin pan What is frequency? makes it vibrate. The number of complete sound You hear a loud waves that pass by in a second and crashing noise. gives us the “frequency” of a sound. Frequency is measured in hertz. High notes have a high Hearing sounds frequency. They make lots of We cannot hear sounds of vibrations, and have a high very high or low frequencies, but some animals can. It is number of hertz. Low notes impossible for us to hear have a low frequency. these sounds because they are outside our hearing range. When a wind Bat instrument is up to 120,000 hertz played, the air Mouse inside the tube up to 91,000 hertz vibrates to make Cat a sound. up to 64,000 hertz Dog Blowing into the pipe up to 45,000 hertz makes the air inside it Young person vibrate all the way along up to 20,000 hertz to the funnel at the end. 413

FMOROCVEEAMNEDNT Push it! A rocket can only take off Playing with force because a blast of energy forces Forces can act in lots it to move. Things move if of different directions they are pushed or pulled, to change the shape or if they are high up to start of something. Try with. The movement they make has a speed in a particular direction. Pull it! this for yourself with a lump of How quickly they speed up depends on how big modeling clay. the force is, and how heavy the moving thing is. Squeeze it! Some forces make things move, but others stop things from moving. Friction is the name for the force that stops movement. The go-cart wheels The heavier the will keep moving passenger is, the until something more difficult it stops them or slows is to push the them down. go-cart along and make it speed up. Roll apart If one girl pushes the other, both will start to roll away from each other. When a force pushes one way, another force pushes equally in the opposite direction. 414

Speed and velocity Down to earth The time something takes to move a distance When you jump, a strong is called speed. Velocity is speed in a particular force called gravity pulls direction. A rocket’s velocity is much greater you back down to Earth. than a snail’s! Earth’s gravity gets A snail moves at about 0.003 weaker as you travel miles (0.005 km) per hour. away from it. On the A fast sprinter runs at about Moon, gravity is much 27 miles (43 km) per hour. less strong, so astronauts A race car reaches speeds of can jump high with heavy up to 257 miles (413 km) per hour. packs on their backs A rocket needs to travel before gravity pulls them at 25,000 miles (40,000 km) per hour. back down again. Pushing is a kind Quick stop of force.The harder the Without friction boy pushes, the bigger the between its wheels and force on the go-cart. the ground, this truck would slip all over the road. The tires have thick patterns, called tread, to help them grip the ground. More pushing Good performance power is needed At high speeds, air rushes over the to start the top of a racing car, pushing it go-cart than to down onto the track. This keep it moving. makes the wide tires grip the track better, so the car can take bends faster than an ordinary car. 415

MAGNETS Magnetic fields Magnets are pieces of A magnetic field is where a magnet has its special material which power. If iron filings are sprinkled around have an invisible force a magnet, they gather together where the that can push things magnetic field is strongest. Two identical away, or pull things poles push each other away, so iron filings towards them. The curve outward. biggest magnet of all is Two different poles the world itself. Scientists think that attract. The iron as Earth spins around, electricity is filings run straight made in the hot metal deep down between them. in its center. This electricity gives Earth magnetic power. Earth has two magnetic N poles, called the magnetic North and S South Poles. Compass needles always point toward the magnetic North Pole. Left out S Magnets only attract some kinds N of material. Not all metals are attracted by magnets. Magnets are fun to The area where play with! These the magnet has magnets are called its power is horseshoe magnets called the because of their magnetic field. curved shape. 416

What are magnets? Make a magnet Scientists think that atoms behave like tiny If you stroke a needle magnets. In a nonmagnetic material, the atoms about 50 times with a face in different directions. In a magnet, all the magnet, it will become atoms face the same way. Magnets lose their magnetic. Stroking the strength if they are hit, dropped, or heated, as needle in the same this makes the atoms face in different directions. direction turns its atoms to face the same way. The ends of Simple compass a magnet are Compasses are made called its poles. with magnets—see for yourself! Tape your magnetic needle to a piece of cork, and float the cork in some water. It points the same way as a real compass needle— toward the magnetic North Pole. N It is hard to push two identical poles together. S The magnetic forces are pushing them apart. N S Every magnet It isn’t easy to Electricity and magnets has two poles, a pull two different Electricity is used to make magnets south pole (S), and poles apart.The which can be switched on and off. The a north pole (N). magnetic forces amount of electric current determines between them the strength of the magnetic field hold them close produced. Reversing the flow of together. electricity will also reverse the magnet’s poles. This electromagnet is used to sort scrap metal. 417

MACHINES Forced apart Wedges are simple machines that split things open. When a force hammers a wedge into a block When you solve a difficult math problem, of wood, the wood you are working hard, but this is not what is pushed apart. scientists call work! In science, work A wedge is a kind of slope. is only done when something is moved— for example, lifted or turned around. Machines make it easier to move things, so less effort is needed to do a job. Bicycles help us move quickly. Like most machines, bicycles are made up of a number of small, simple machines. Wheels, axles, pulleys, gears, levers, slopes, and screws are all common simple machines. Fulcrum Saddle sore? Easy does it It is possible to ride a long Levers make it easier to move things. way on a bike—between A seesaw is a kind of lever. It balances 1922 and 1973, a Scot on a point called a fulcrum. The girl’s weight named Tommy Chambers moves the box up. Moving the fulcrum closer cycled 799,405 miles to the box will make it easier to lift. (1,286,517 kilometers)! Cables link the brake levers to the brake blocks. Pulling the brake levers makes the brake blocks stop the moving wheels. Brake blocks press against the wheel.They use friction to stop the wheel from moving. Wheel genius The wheel spins, The wheel is one of our most or rotates, important machines. Two wheels can around an axle. be joined together by a pole called an axle. A small movement of an axle makes a big turn of a wheel. 418

Difficult Easy Get into gear Uphill climb A toothed wheel that turns another Slopes are simple machines. They toothed wheel is called a gear. make it easier to move things onto a Gears change the speed higher or lower level. A screw is a kind or direction of the of slope. If you could unwind the spiral moving part of a grooves on a screw, they would machine. The small flatten out as a slope. wheel spins around twice as fast as the big wheel, turning in the opposite direction. A chain links the gears and the pedals to the back wheel. A small movement of the pedals is turned into a bigger turn of the wheel. The chain is part of a pulley system. Pedal power Light as a feather? is the force that Lifting up a weight with your bare hands gets you started. is hard work. It is much easier to lift a weight by pulling down on the ropes of a pulley. If you double the number of pulley wheels, the same amount of effort will lift twice as many weights. 419

EMNOGTINORESS AND Engines and motors provide power to make things move. Motors usually run on electricity, and often drive small things, such as fans or hairdryers. Engines are usually more powerful, and run on heat. In steam engines— the first real engines—heat boils water to make steam, and the steam pushes the engine around, just as steam in a pan of boiling water pushes up the lid. Cars have “internal combustion” engines. In these, the engine is pushed around by the gas produced from burning gasoline inside the engine. Boiler to make steam Letting off steam Brightly colored steam traction engines like this one were often seen at fairgrounds up until around the middle of the 20th century. The steam traction engine drove the rides and made electricity for the lights. Electric power Electric motors work by magnetism. An electric current passing through a coil of wire turns the coil into a very powerful magnet. If the coil is set between another magnet, it is driven around at great speed to power machines, such as your hairdryer. Magnet Jet power Most modern airplanes have jet Coil of wire engines. These push a blast of hot spins around air out of the back, which drives the plane forward at enormous speed. 420

Gasoline engine Fuel is drawn Four steps This is a model of an internal into the engine In most cars, the engine works combustion engine, just like through this in four steps, which is why it is those used in most cars today. inlet pipe. Fuel is constantly drawn into called a 4-stroke engine. the engine’s cylinder where it is set afire by an electric spark. Cylinder The explosion pushes the piston down and turns This is the spark plug the engine. that lights the fuel. This is the 1. Fuel and air pass cylinder where into the cylinder. the fuel is burned. Old burned fuel is pushed out through this exhaust pipe. This is the piston. It has been pushed down by the burning fuel. 2. The fuel and air are squashed. Spark plug 3. The spark sets fire to the fuel. Cooling fins This is the crankshaft. It Spot the engine turns around and around as You can find a machine’s the piston goes up and down. engine in all sorts of places. The engines here are colored green. 4. The burned gases are pushed out. Electric car Magnet-powered train Propeller aircraft Jet fighter 421

WAMR ACHINES An aircraft carrier Hand grenade Modern armies have all sorts of weapons, from rifles Going bang! and grenades for fighting a single enemy, to bombs and missiles for attacking large targets. Soldiers can go into battle riding in a tank—a huge gun on wheels protected by heavy armor plating. But nothing can protect against nuclear bombs, the most powerful weapons of all. The main gun can fire This is the turret. It turns powerful shells that around so the gun can be will travel nearly 10,000 aimed in any direction. feet (3,000 meters). Gunpowder was first used in China more than 1,000 years ago for making fireworks. In 1605, Guy Fawkes tried The tank can carry a huge to blow up the English amount of fuel—around 420 Parliament with gunpowder. gallons () 1,900 liters. But it is only enough to drive about 275 miles (440 kilometers) at 25 miles (40 kilometers) an hour. The commander sits at the top. The driver sits inside The gunner aims the main The loader loads at the front, and uses gun using a thermal the main gun with mirrors to see what is imaging sight.This picks explosive shells. He happening outside. up the heat given out by also operates the radio. enemy targets. In 1867, Alfred Nobel 422 invented a very powerful explosive called dynamite.

Runway at sea Getting up speed Aircraft carriers are huge ships Muskets were used by soldiers in the 17th with flat decks which war century. They needed reloading after each shot. planes use for taking off and landing. The carriers sail close Handguns like this to enemy coasts so the planes Colt 45 were carried about can launch attacks. 150 years ago by cowboys in Heavy steel armor up to the American west. They five inches (13 centimeters) could fire six bullets without One of the crew uses a thick protects the crew being reloaded. machine gun to defend from enemy fire. the tank against enemy aircraft. Machine guns were invented in 1884 by Sir Hiram Maxim. They could fire dozens of bullets one after the other. The wheels run Destruction caused by a Nuclear weapons inside tough metal nuclear bomb in Hiroshima, A single nuclear bands called caterpillar Japan, 1945. bomb can destroy a tracks.To steer, the whole city, and the driver makes one track run radiation it leaves faster than the other. behind can kill people and animals A nuclear explosion years later. There 1. As the bomb are now enough explodes, it nuclear weapons to destroy the world. makes a giant 2. The 3. The 4. A cloud explosion blast of rubble and fireball. shakes and fire dust mushrooms the city destroy up high into below. buildings. the sky. 423

COMMPUATGEIRC Computers are the world’s smartest machines. Inside a computer are thousands of very tiny electronic switches, a bit like light switches. By switching them on and off in different combinations, computers can perform all kinds of tasks. They are used everywhere, from factories and hospitals to stores and offices. Some guide aircraft, ships, submarines, and spacecraft. Others are used just for having fun, such as playing games and watching movies. Keeping your head up Seeing inside A jet fighter pilot must not take Doctors can use a CT (computed tomography) their eyes off the view ahead, even scanner to see inside a patient’s body. A CT for a second. All the information they scanner uses X-rays to create images of “slices” need to control the plane and fire through the body. These are put together on a at targets is fed to a computer, and computer to create a 3-D image, which doctors projected onto the pilot’s face mask. use to see what needs treating. This is called a “head-up” display. 424

Bytes and megabytes Computers can help with homework, or steer a rocket into space. Pocket brain Laptop computer The first electronic computers filled a large room. Now there are smarter and faster computers that can be held in your hand, such as this smartphone. Shrinking switches Tablet computer The switches in Global positioning computers have gotten steadily smaller, and system (GPS) more complicated. The first computers had glass valve switches as big as your thumb. Computers now have Gaming device microprocessors.They are Data center only the size of a small fingernail, yet packed with billions of switches. 425

ROBOTS The camera in Asimo’s head allows him to see objects, plan routes, and even recognize faces. Robots are machines that “think” with a computer brain that tells them what to do. Once they have been programmed, they can work entirely by themselves. Some people believe that one day we will be able to make robots that can do everything a human can—and they may even look like humans. Right now, though, most robots in use today are nothing more than mechanical arms or cranes. Mechanical men Asimo automatically Automatons are smart machines bends or twists his body that move kind of like humans to keep balanced while or animals. This one was made walking or running. for a fair in Victorian times. Factory hand A factory robot is often just a moving arm. But a robotic arm can hold things, screw them into place, weld them, and check that they work. It can replace lots of human workers. Robots at work and play Robot Robot dog Bomb- Robotic space disposal robot arm probe 426

There are force sensors in Asimo’s wrists, so if someone shakes his hand, he can tell if he needs to move closer or step back. Amazing Asimo Handy robot The first walking Asimo has thumbs just like robots made by a real person, so he can hold Honda in the 1980s objects, carry trays, open have led to Asimo: doors, and even pour a drink! a robot that interacts Asimo can walk, with humans and run, and climb up can help them in and down stairs. the home or office. This “backpack” is Asimo’s power source, which lasts for an hour on a single charge. Robots in space NASA has sent the first humanoid robot into space. Robonaut 2 is on the International Space Station, doing jobs that are too dangerous or mundane for humans to do. 427

ENERGY Oil rig AND INDUSTRY In today’s world there are thousands of different industries, and they are divided into three groups. Primary industries, such as farming and mining, take raw materials from the earth. Manufacturing industries make, or manufacture, things from the raw materials. Service industries are made up of people who sell these goods or supply skills, such as nursing or teaching. All industry needs energy, so as the world becomes more industrial, it needs more and more energy. Energy for industry comes mostly from fossil fuels—coal, oil, and gas. Since these are quickly being used up, we are now switching to solar, wind, and ocean energy that will last forever. Wind is a type of endless energy. Oil Coal Natural gas Nuclear energy 428

Iron ore Steel is made from iron ore. Cars are made from steel. Microchips manufactured on a silicon slice. Nylon rope Stores are part of the service industry. Factories put things together, one step at a time, in production lines. 429

COAL Big wheels, called winding gear, lift the coal bucket to the surface. Like layers of icing in a cake, there are bands, or seams, of coal in the rocks Opencast Fans suck stale beneath the ground. mine air out of the mine Some seams are near Scoop shaft.This drags enough to the surface fresh air down the to be scraped out other shaft. with diggers.This is called opencast mining. But most Cut it out seams are found deeper down, and Each scoop on have to be dug up by miners using this coal-cutting machine is big enough to hold a car! massive machines. About 40 percent of the nine billion tons of coal mined each year is burned in power stations Roof supports to generate electricity. Face facts The part of a seam where coal is being cut is Cooking coke called a face. Coal is put into giant ovens The coal is and baked at ripped out by a more than spinning cutter 1,650°F (900°C). with steel teeth. When the oven Coal door is opened, face A big bucket carries coke topples out. Coke is needed coal to the surface. to make steel. Coke is coal minus Water is Conveyor belt tar, oils, and gases. sprayed onto Pumps take The tar that collects at the bottom the coal to water from of a coke oven is used to make soap! cut down the the bottom coal dust. of the mine. 430

Air in Computer Down to earth control room Not all coal is the same. Hard coals, which are found deeper underground, release more energy when they burn. The coal is washed and separated into different-sized lumps before it Burning to go Half-squashed coal, or Nonstop trains peat, is made into fuel bricks. leaves the mine. take coal straight to the power station. Cages carry miners All aboard! Soft, crumbly brown coal down a deep shaft. Miners travel on trains is burned to make coke. The main to coal faces that are shaft was many miles away blown out of from the shaft. the rock with explosives. Most of the coal Black bituminous coal is in this seam has burned to generate electricity. already been dug out. Long tunnels are A breeze can always dug to reach new be felt in the tunnel coal seams. as the air moves through the mine. Anthracite coal is used in houses and factories. Davy’s Seeing the light safety lamp Miners once worked by candlelight, but the flames often set fire to the Boring! Big machines explosive gases that build chew through up in tunnels. In 1815, a safety lamp was the rock to open invented. Its flame up new tunnels. was kept behind a wire mesh. Modern Mine shafts can be lamps are even 4,000 feet (1,200 safer, as they are meters) deep. battery powered. 431

OIL This is a model Unwanted gas is of an oil platform burned from the top in the North Sea. of a tall tower. In the rocks under hot deserts, snowy Two hundred Drilling pipes plains, and stormy seas, there is buried people live and hang from a tower treasure: a “liquid gold” called oil. work on this called a derrick. Most of this sticky, black fossil fuel oil platform. Helicopter is used for energy, but 12 percent Lifeboat of each barrel is turned into chemicals Some oil is and plastics. All oil is brought to the piped into Sandstone surface by drilling deep a gigantic, underwater holes called wells. On land this is fairly easy, but storage at sea, platforms as tall as tank. skyscrapers have to be built. Gas Sandstone with oil Natural Every day, one An arched layer of Solid “sponge” gas quarter of a million oilproof rock, such Oil is found in the Trapped barrels of hot, as granite, traps oil tiny spaces in rocks oil freshly drilled oil underneath it. such as sandstone. are pumped into This oily layer is the hollow concrete Wells fan out often sandwiched legs to cool down. to reach the oil. between water and a layer of natural gas. Water Cooled oil is piped ashore. Each marble stands for a grain of rock. Explosives are used to make A boring bit cracks in the rock A sharp-toothed metal cutter, so that oil can flow called a bit, bores through rock into the wells. to reach oil. Drill bits are Oil replaced twice a day, as Water they wear out quickly. During drilling, chemicals are pumped around the bit to carry rubble up to the surface. 432

Only way out Oil at sea A 769-mile-long Huge structures, (1,287-kilometer-long) called rigs, drill down pipe snakes across the to find oil. At sea, snowy wastes of Alaska. some rigs float on Oil takes a whole week the surface, while to flow down the pipe to others stand on the reach an ice-free port in sea bed. Look how big this the South. rig is compared to the Statue of Liberty! Huge tankers “plug Tankers can into” this oil store take oil all Jack-up rig to take on oil. over the world. Anchors keep Pump it up Drill ship the oil store Not all oil gushes to the surface on the sea bed. naturally. Some is pumped up by machines called nodding donkeys! This “donkey” has been painted to look like a grasshopper. This zigzag break in Semisubmersible rig the picture is to show that oil is usually found under Gas gushes thousands of yards of rock. out when the Wildcat wanted? pressure is Before a well is dug, geologists released. must be sure that the rocks Bubble trouble below the ground are the right Just like the shape to trap oil. A test drill, fizz in soda pop, or “wildcat,” is only started bubbles of natural if the surveys and satellite gas are trapped in oil. pictures look good. If there is enough gas, it is piped ashore. If not, 433 the gas is just burned.

NATURAL GAS In 1918, a gas was discovered in an What a whiff ! oilfield in Texas. It was named natural The journey Natural gas gas because it replaced a gas that was begins at has no smell. manufactured from coal. This new fuel a gas rig. Chemicals are is now used in factories and homes all added to it so over the world. Natural gas travels a long that leaks can way before it reaches your stove, to burn be smelled. as a bright blue flame. It has to be released from deep below the ground, cleaned, and piped countless miles. Mostly methane Gas terminal Natural gas contains three different gases. Butane and propane are taken out at a gas terminal. Giant fans waft Methane, the part that natural gas burns best, is sent along the pipes. through pipes to houses and factories. Pipe Butane gas “Pig” camping stove Cool it If it is cooled into a Soil Ships take methane liquid, a balloonful Very important pig to places that are of methane gas can not connected to fit into a space the “Pigs,” not people, check pipelines. The gas size of a pea. natural gas pipes! is cooled into a liquid Methane is cooled to A “pig” is a computer so that it takes up 600 -260°F (-162°C) to on wheels that times less room. make it turn into a liquid. whizzes down pipes to pinpoint cracks Methane tank and other problems. 434

On the way up What size pipe? This big building, called a rig, gathers up gas that flows from deep under the sea bed. The drill to reach the pocket of gas may be nearly four miles (six kilometers) long. The roof floats on top Some gas is stored near You could stand of the gas. So the homes to supply sudden up in the pipe that lower the roof is, daily demands—such as travels between the the less gas is left. at dinner time! rig and the terminal. The plastic gas pipe is dragged through the tunnel by the “mole.” Iron pipe Road Gas is sent The “mole” smashes through pipes through the earth like to homes and a pneumatic drill. factories. A dog could fit into the pipe that links factory pipes to gas-terminal pipes. Pumping stations “Mole” hole The pipes that take keep the gas moving. gas to factories is roomy enough for Growing gas a cat to sit in. Farms off the coast of California grow a Moles beat diggers giant seaweed called Small pipes can be laid kelp. It is harvested without digging up streets by three times a year using a rocketlike machine A mouse could fit by special ships and called a “mole.” Its route is into the small plastic then put in tanks guided by a computer. pipe that goes into and left to rot. The your home. decaying kelp gives off methane gas. 435

NUCELENAERRGY Not so fast This drawing shows very simply how neutrons whizz around a nuclear reactor and crash into uranium atoms in fuel rods. Atoms are the tiny particles that make up the whole universe. Enormous amounts of energy are locked inside atoms. When billions of Super fuel One handful of pure uranium can release uranium atoms are torn apart 2.The splitting as much energy as in a nuclear power station, the uranium atoms 72,000 barrels of oil! energy that is set free can inside the fuel rod “shoot out” new boil water. Steam from this hot water is used neutrons which to generate electricity. People worry about travel at 9,900 nuclear power because when the energy miles (16,000 km) is released from an atom, deadly rays, called radiation, also escape. per second. 1. Energy is A neutron collides Water warms up released when with an atom. Fuel rod neutrons hit atoms in the fuel rods. The center of the uranium atom splits in half. Energy and Two or three new neutrons radiation escape. Each one can collide with another atom and set free more energy. Old fuel Cold rods are water Fission division radioactive Cool it The heart of an atom, called a Fuel rods are replaced nucleus, is made up of neutrons and “garbage.” every few years. Before the reusable uranium can protons. These are held together by be removed from them, energy. When an atom is split, some the rods are cooled in of this energy is set free. Splitting an a special pond. atom to release energy is called fission. 436

Inside this building, a turning The nuclear turbine generates electricity. reactor is in here. Moderator A powerful building The reactor is under The nuclear reactor is surrounded this red steel floor. by thick concrete walls. These make sure that dangerous radiation does not escape. 3.The neutrons If the neutrons Safe deposit? collide with atoms travel too fast, they A typical nuclear power in the moderator.This will just whizz past station produces about 20 slows them down to the uranium atoms bathfuls of very dangerous just 1.2 miles (two in the fuel rod, radioactive waste each year. kilometers) per second! and not release It is made into a sort of 4.This metal rod any energy to glass and poured into steel is a neutron stopper! heat up the water. tanks, which are coated in It is pulled in and concrete and buried. out to let just the Control rod Less dangerous waste right number of is buried in barrels. neutrons through. Hot If too many neutrons pass water the control rod, too much Sunny future 6.The powerful jet of energy is released, and the When superhot steam turns a turbine reactor could explode. atoms collide, they to generate electricity. fuse together and set 5. Heat passes from energy free. It is this the hot water inside the fusion that makes the reactor to this flow of sun shine. Scientists cold water.The cold are trying to build water boils into steam. “suns” on Earth by firing lasers at atoms. Laser beam 437

RENEWABLE ENERGY When oil, gas, and coal run out, people will need other sources of energy to fuel What a gas! their cars and light their houses. Wind In some countries manure and water are already being put to is collected, dumped into work, but the best hope for a renewable containers, and left to rot. supply of energy is the sun. Light and The gas it gives off is heat from the sun pour down onto piped into homes and used Earth all the time. Today, sunshine for cooking and heating. runs everything from watches to power stations. One day scientists hope to collect sunlight in space, and beam it back to Earth! Falling for you Spinning shaft Trick of the light The energy of the This is the world’s first solar crashing water at Niagara power station. It was built in Falls has been used since 1969 at Odeillo in France. 1759. The cascading water Electricity is generated forces huge paddles, by using reflected called turbines, to move sunlight to boil around. The spinning water into steam. turbines turn a shaft to generate electricity. This enormous Whooshing water pushes mirror is curved the paddles around. so that all the sunshine that hits it is reflected onto one small spot at the top of the tower. Computers keep the 63 minimirrors facing the sun. Not alone The solar power station is faced by 63 small, flat mirrors. They reflect extra light onto the main mirror. 438

Whizzing in the wind Strong, steady winds can be put to work turning windmill blades. As the blades spin, they turn a shaft that generates electricity. These modern windmills come in several shapes. Groups of them are called wind farms. Blades Reflection of A solar power Shafts Electricity generators the ground station does not need a chimney—there are no fumes or ash! This mirror is 140 feet (42 meters) wide. It is built onto the side of a building. Water inside this tower turns to steam. It can get as No need for a plug hot as 6,900°F Solar cells, made from slices (3,800°C) inside of wafer-thin silicon, turn this tower. sunlight into electricity. This remote jungle telephone is powered by several solar cells. Sunlight knocks electrons from the top layer to the bottom layer of silicon.This generates an electric current that is collected by the metal layers. Sunlight Metal Silicon Metal 439

ELECTRICITY Electricity is used as a way of moving energy from place to place. It can take energy from burning a fuel, such as coal or gas, in a power station into your home to work your television. Most electricity is generated in machines. Small machines, called dynamos, light the lights on bikes. Huge generators in power stations light whole cities. Pedal power works a dynamo, but steam produces the electricity in a power station. Mighty machine This steam is made by using the heat from The big blue generator inside this power station burning fossil fuels or splitting atoms. is about ten times Sunshine, falling water, and whirling as tall as you! Dynamo windmills can also generate electricity. 5.The moving magnet creates This magnet Chimney an electric spins around 3. Steam surges 4.Turbines turn current in huge because it is from the boiler a massive magnet coils of wire. fixed to a rod into the generator. 50 times per that touches the It pushes around second. turning wheel. huge paddles, First called turbines. transformer Electricity is generated 2.The burning in this coil of wire by coal makes water the spinning magnet. turn into steam. A pile of coal 1. Coal is crushed as heavy as and then blown into 40 elephants the boiler to burn. is burned each hour. Choice of fuels A condenser turns A power station uses the hot steam into just one sort of fuel to Oil hot water. generate its electricity. This one burns coal, but Uranium The cooling tower cools 440 the hot water so that it other power stations use oil, can be used again. natural gas, or nuclear fuel. Natural gas

In charge Power stations can’t be built near all the places that need electricity. So the electricity generated flows into a network of cables, called a grid. At the touch of a button, electricity is made to flow to wherever it is needed. Electricity is dangerous, Second Electricity cables are so tall pylons hold the transformer laid under the ground long cables high above in towns and cities. the ground. A substation makes Watt is power? electricity safe for you The speed at which to use in your home. different machines use energy is Aluminum cable measured in units called watts. Energy travels down the cables at about Electric clock 155,000 miles (250,000 (10 watts) kilometers) per second— almost as fast as the Vacuum cleaner speed of light! (900 watts) These children Each ball Going up or going down? Welding machine are pretending is a “parcel” Machines called transformers change the (10,000 watts) to be tiny parts of electrical strength of an electric current. The current of atoms, called energy. that flows between pylons has to be electrons. decreased to stop the cables from melting. Pass the parcel People once thought that electricity flowed like water, which is why it was called a current. In fact, energy moves along a cable more like balls being passed down a line! 441

METALS Limestone Crushed Coke iron ore Metals are found in the Blast ground, hidden in certain Steel from iron furnace Iron has a lot of carbon in rocks called ores. Tin, copper, it, which makes it crack Hot Iron ore and iron all have to be taken easily. If some carbon is air out of their ores before a factory removed, iron turns into Iron can melt and shape them into a can, superstrong steel. This change starts pan, or car. Pure metals, however, are in a blast furnace. usually too weak to be used in industry, and have to be mixed together to make Coke, limestone, and iron ore heat better metals called alloys. Lead is soft, up and turn into iron and tin breaks easily. Together they and a waste material can make a strong, tough alloy called slag. Slag known as pewter. Copper pan Not natural Brass cannot be dug out of the ground. It is an alloy made by mixing together two weaker metals, copper and zinc. Brass is Zinc-coated stronger bucket and wire than zinc or copper. Precious metals 1. Blasted iron ore Gold and silver are A stream of iron is flowing from used to make much this huge oven, called a blast furnace. more than just jewelry. It has been burned out of iron ore Gold is sprayed onto by blasts of hot air. an astronaut’s visor to reflect sunlight. Silver is used in electronic equipment because it carries electricity very well. 442

Big dipper Plane wrapper Steel girders are dipped in a bath Aluminum is a marvelous of melted zinc to stop them from metal. Thin sheets are rusting. This process is known wrapped around chocolate as galvanizing. to preserve its taste. Thick sheets are made into jumbo jets. Aluminium is used to make planes because it does not rust, and it is very light. The aluminium is made as stiff as steel by adding a little copper. Iron waiting Oxygen rushes Rust buster to be converted down this tube. You would not want to Upright eat with rusty cutlery! converter Scrap iron can So chromium is added In 40 minutes be put into the to steel to make an alloy the converter converter, too. called stainless steel. can make 385 tons of steel. Tipped-up When the strips of converter steel are cold they can be squashed by rollers into flat slabs. Hot steel 2. Iron in, steel out 3. Taking shape The liquid iron is poured into a converter. Hot, freshly made steel is poured into After a powerful jet of oxygen has burned a big tray. When it has almost set, out the impurities and most of the carbon, nozzles are opened and steel oozes the converter is tipped up to pour out steel. out, like toothpaste out of a tube. 443

MAKING A CAR Every few seconds, somewhere in the world, a brand-new car rolls off a production line Stamp it out and out of a car factory. Each car is made Sheets of cold steel from raw materials, such as iron ore, sulphur, are stamped into Model T and sand, which have been shaped into more shape by machines than 30,000 parts! Most of this “jigsaw puzzle” is put called presses. A together on a kind of giant conveyor belt. Each area press room can be of the factory puts on a few particular pieces; for the size of three example, the body shop adds the roof, but football stadiums! never the seats.The first car made like this was the Model T Ford. Each car body is made from more Press than 20 pieces, or panels, of steel. Steel The start of the About 65 percent “conveyor belt.” of a car is made of iron and steel. Start with steel A roller test is used Apart from their color, Steel is the most to check that the all the cars made on this important ingredient car is working. production line are the same. for making cars. Rolling mills press hot steel into thin sheets. These are then rolled up and sent to car factories. Cars are washed and polished before Built to bounce they leave the factory to be sold. To make your journey Ready to go smooth, tires are made Cars were invented toward the end of the of rubber and 19th century. There filled with air. are now more than Strands of steel or nylon one billion of them. strengthen the tires. 444

Robot The pressed Robots in charge welder steel panels The steel sides, roof, and doors have form a rigid to be joined together. This is done by box to protect welding—making the metal melt and the passengers. stick together. Using more than 1,000 welds, robots can build a car body in just 42 seconds. Heavy cars use more fuel. Robot Mechanical Monets So more and more metal painter Cars are painted by parts, such as bumpers, The doors are removed robots with sprays. are being made of plastic. so that the inside can be The robots are not reached more easily. harmed by paint fumes, and can put paint on quickly and accurately. Bare steel Top base coat The car is lowered onto an engine, which Fifteen coats was built on a separate production line. of paint are put This may have been in another country! on each panel. Robots add windows. Together at last Each worker Pile up The engine is the repeats the same A new car may not heart of the car, job over and be as new as you think. but it is not added over again. Up to 25 percent of to the body until the steel may have come near the end of from old cars! Recycling the production line. scrap steel saves raw materials and energy. 445

CHINEDMUICSTARLIES Soap, fertilizer, and glue are just a few of the useful products of the chemical industries. Oil refinery They are made by combining different substances. Crude oil (unprocessed oil taken straight from the Distillation ground) is the main raw material for these tower industries. The carbon and hydrogen in oil can 230°F be made to combine in different ways to make (110 °C) more than half a million things, such as gas, paint, or pills! This manufacturing starts in large factories called refineries. Split it up! Cooling oil drips Crude oil is split into useful oils inside from the edge of a distillation tower at a refinery. The this “saucer” into oils are separated by being boiled into the tray below. a gas, and then cooled back into a liquid. Liquid again Kerosene is 360°F If you put a saucer the fuel used (180 °C) over a cup of steaming hot The cloud of crude oil liquid, droplets collect on by airplanes. gets cooler and cooler as the saucer. The liquid has Lubricating it wafts up the tower. turned into steam and then cooled back into a liquid oil makes At 725°F (385°C), when it hit the cold saucer. machines run crude oil turns into a gas. smoothly. Very hot Crude oil is pumped liquid turns into a furnace to be into a gas. boiled into a gas. Gas cools into a liquid. 446

All change Catalytic cracker Chlorine keeps the Oil is made up of long chains of carbon water in swimming and hydrogen atoms. Useful chemicals, called petrochemicals, are made by pools clean and breaking up these chains. This is done safe to swim in. by heating the oil in tanks called catalytic It is made in a crackers. The small chains can be used factory by passing to make useful things such as shampoo. electricity through salty water. The electric current makes the atoms in the salt and water Carbon Hydrogen atom atom rearrange, and produces chlorine. Hydrogen atoms are forced between the carbon atoms to break up the chain. The gases that come out of the top of the tower are made into plastics. Shampoo Plastics Antiseptic One-fifth of each Gasoline is the most liquid barrel of crude common fuel used Nail oil separates to power cars. polish into gasoline. Diesel is the When the cloud fuel used by Super sulphur of crude oil reaches this many trains. About 165 million tons of height, it is cool enough Dark industrial sulphuric acid are used every for diesel to turn oil is burned in year to help make things such as into a liquid. factories and fertilizer, paper, and explosives. A different oil power stations. This acid is made by heating flows out of each a yellow rock called sulphur. pipe because all the oils in crude oil cool into liquids at different temperatures. Bitumen is the first oil to flow out of the tower. Thick, sticky bitumen is spread on the surface of roads. 447

PLASTICS Get set or go? Some plastics are like bread! Once they have been “baked” they Plastics are amazing materials. They don’t cannot be reheated and rot like wood or rust like some metals, and made into new shapes. A mug they are light and easy to shape. Plastic pens, made of melamine will not change shoes, and even surfboards are all made from shape when hot drinks are poured into it. Polystyrene and polythene are more like chocolate—they oil or coal. Chemicals are taken from these can be melted again and fossil fuels and turned into small, white pellets. again. Each time the mixture cools, it sets These are then melted and blown into the shape of the to form bags or rolled flat to mold it has been make floor tiles. Buckets, poured into. bowls, and boxes are usually shaped by being injected The two halves of the steel into molding machines. mold lock tightly together. Bowled out Cold water cools Plastic bowls are made by injecting down the plastic after it has been melted plastic pellets into the space molded. between two halves of a steel mold. The plastic cools inside the mold, and sets into a bowl shape. Coloring and Heaters help New Mold plastic pellets to melt the bowl are poured in. pellets. A screw pushes the squashed, hot pellets into the mold. Melted plastic Each bowl Two handfuls of Temperatures of 540°F needs this polypropylene plastic (280°C) are needed to melt amount of pellets make each bowl. the pellets and make them coloring. flow into this mold. 448