by Ann J. Jacobs

Scott Foresman Science 3.13

Genre Comprehension Skill Text Features Science Content

Nonfi ction Main Idea and Supporting Details

Captions

Charts

Call Outs

Glossary

Energy

ISBN 0-328-13844-4

Vocabularyabsorb

electric charge

electric circuit

electric current

kinetic energy

What did you learn?1. What kind of energy is stored in a battery?

2. While running in place, the chemical energy stored in your body would change to what kind of energy?

3. Why does rubbing a balloon attract pieces of paper?

4. In this book you have read about thermal energy. Write to explain how thermal energy moves. Use examples from the book in your answer.

5. Main Idea and Supporting Details What is the main idea of the last paragraph on page 2? What details support it? Photographs: Every effort has been made to secure permission and provide appropriate credit for

photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd)Opener: Scott T. Smith/Corbis; Title Page: Spencer Grant/PhotoEdit; 2 Martin F. Chillmaid/Photo Researchers, Inc.; 3 Doug Wilson/Alamy Images; 4 Brad Wrobleski/Masterfile Corporation, Stone/Getty Images; 5 Fotopic/Index Stock Imagery; 6 (CC) AGStockUSA, Inc./Alamy Images, (CR) Henryk T. Kaiser/Index Stock Imagery; 7 (CL) Lester Lefkowitz/Corbis, (CCL) Mark L. Stephenson/Corbis, (CC) Mark C. Burnett/Photo Researchers, Inc.; 8 Ted Grant/Masterfile Corporation; 14 (CL) Jeff Greenberg/Index Stock Imagery, (B) Norbert Wu Productions; 15 Pierre Arsenault/Masterfile Corporation; 16 Daryl Benson/Masterfile Corporation; 17 Craig Tuttle/Corbis; 19 Joel Sartore/NGS Image Collection; 23 (CLT) Alan Schein Photography/Corbis, (CL) DK Images, (CLB) Martin F. Chillmaid-Spencer Grant/Photo Researchers, Inc.

ISBN: 0-328-13844-4

Copyright Pearson Education, Inc.

All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05

potential energy

reflect

refract

thermal energy

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Energyby Ann J. Jacobs

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2

What is energy?Energy

Energy is the ability to do work or cause change.

Work is when force causes an object to move. Most of

our energy comes from the Sun. The Sun heats Earth.

The Suns light energy makes plants grow.

We use many other forms of energy too. Sound

energy comes from a CD player. Chemical energy runs

a cars engine. Electrical energy runs many things in

this kitchen.

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3

Stored Energy Stored energy is potential energy. It can change

into another kind of energy to do work or cause a

change.

Fuel, such as natural gas, has potential energy.

Long ago, plants made food using energy from the

Sun. The plants died and turned into fossils that are

used as fuel. When we burn this fuel, we free potential

energy. Work is possible.

When you use batteries, you release potential

energy. The stored energy in food, fuels, and batteries

is chemical energy.

Batteries and gasoline both contain stored energy.

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4

Energy of MotionPotential energy can change to kinetic energy.

Kinetic energy is the energy of motion. A car burns

gas. The potential energy stored in the gas changes to

kinetic energy. The car moves.

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5

A skier rests at the top of a hill. He has potential

energy. Then he slides down the hill. His potential

energy changes to kinetic energy.

A skier uses a lot of energy. But he can replace it

by eating food. The gas a car burns to create energy

cannot be easily replaced. Fossil fuels, such as gas,

are not renewable.

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Chemical Mechanical

6

How does energy change form?Changing Forms of Energy

Energy changes from one form to another all the

time. Your body stores potential energy in the form

of chemical energy. This chemical energy changes to

kinetic energy when you move.

Using EnergyThe kinetic energy of your arm cannot make

a light bulb burn bright. But it can be used to flip a

light switch. This changes

electrical energy to light

energy. But not all the energy

gets changed. Some energy

is given off as heat. The light

bulb gets hot.

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Electrical Light Thermal

Forms of Energy

7

People use machines to change forms of energy

too. An electric toothbrush sits in a base that plugs

into an electric outlet. The toothbrushs battery stores

electrical energy as chemical energy. The chemical

energy changes to electrical energy when you turn on

the toothbrush. The electrical energy then changes to

mechanical energy as the toothbrush moves.

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Ways That Energy Travels Energy can move from one place to another.

A moving object, such as a ball, has energy. You

can feel the energy when you catch the ball.

Energy can also travel as waves. The waves are

shaped similar to the waves on a moving rope. Look

at the rope on the next page. It is moving from side

to side. Energy makes this happen. It moves from one

end of the rope to the other.

Light and other forms of kinetic energy move as

waves. Bigger waves carry more energy.

8

Ocean waves carry energy.

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9

Parts of a WaveHow much energy does a wave have? How far

the wave is from its midpoint shows its energy. You

measure the distance from the midpoint of the wave

to the high or low point of the wave. The top of a

wave is called a crest. The bottom is called a trough.

Wide waves have lots of energy. Narrow waves have

less energy.

You should also look at the length of a wave. The

wavelength can be the measurement from the top of

one crest to the top of the next crest. Short waves have

more energy. Long waves have less energy.

Crest

Wavelength

TroughDistance from midpoint of wave

Distance from midpoint of wave

Midpoint

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10

What is heat energy?Heat Energy

Matter is made up of moving particles. Particles

move because they have energy. The energy of moving

particles in matter is called thermal energy.

Thermal energy moves as heat. It moves from hot

things to cool things. Put a spoon into a hot drink.

Heat from the drink moves through the cool spoon.

Soon the spoon is as warm as the drink. The flow

of energy stops when the drink and spoon are the

same temperature.

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11

Sources of HeatHeat is given off when energy changes from one

form to another. The burner under the pot below

changes electrical energy to heat. A burning match

changes chemical energy to heat.

Try rubbing your hands together. The friction

caused by rubbing gives off heat. There is heat every

time energy moves.

A burning match is very hot!

Heat moves from the water to the frozen vegetables.

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12

Effects of Heat on MatterHeat energy affects matter. You can measure the

effect of heat on matter. Put some ice out in a room

that is steady at a temperature above 0C (32F).

Look at the ice a few times during the hour. Measure

and record the amount of ice that has melted. Record

the time when all the ice has melted. Record the

temperature. Time is one way to measure how this

heat energy changed the ice.

How has this ice changed?

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13

Water evaporates if more heat is added to it. The

water turns into a gas called water vapor. Liquid water

changes in another way at 100C (212F). Heat makes

the water boil. The water takes up more space when

it boils. Then it evaporates and becomes a gas. Hot

bubbles of g