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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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