3 13 energy (physical science)

absorb electric charge electric circuit electric current kinetic energy What did you learn?. While running in place, the chemical energy stored in your body would change to what kind o

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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

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Physical Science

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

ì<(sk$m)=bdieej< +^-Ä-U-Ä-U

Physical Science

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absorb

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

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

Energy

by Ann J Jacobs

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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 Sun’s light energy makes plants grow

We use many other forms of energy too Sound

energy comes from a CD player Chemical energy runs

a car’s engine Electrical energy runs many things in

this kitchen

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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Energy of Motion

Potential 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

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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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 Energy

The 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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People use machines to change forms of energy too An electric toothbrush sits in a base that plugs into an electric outlet The toothbrush’s 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.

9

Parts of a Wave

How 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

Trough Distance from

midpoint of wave

Distance from midpoint of wave

Midpoint

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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

11

Sources of Heat

Heat 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 Matter

Heat 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 0ºC (32ºF)

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?

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 100°C (212°F) Heat makes the water boil The water takes up more space when

it boils Then it evaporates and becomes a gas Hot bubbles of gas float to the top of the water Hot water droplets called steam come out of the bubbles

This water is boiling Some

of the water is leaving as steam.

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What is light energy?

Sources of Light

Most energy comes from the Sun The Sun’s energy

reaches Earth as waves The waves have different

amounts of energy Some of these waves affect us We

can see and use light energy

Chemical changes also make light Gas in the lamp

below gives off light as it burns The fish below gives

off light too Chemical changes in the fish’s body

make light

14

The lamp and this fish are both a source of light.

Electricity gives us light It makes the wire in a light bulb hot The hot wire glows and gives off light

Most things that give off light give off heat too

The Path of Light

Light moves in all directions from where it starts

It moves away from its source in straight lines Light moves this way until an object stops it Light cannot

go around objects Objects that get in the way of light’s path cause shadows

15

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How Light Changes

Not all objects block light Light can pass through

some things, such as a window

All objects reflect light This means light bounces

off the object and moves in a different direction Some

things, such as a lake, reflect light better than other

things Why? They have flat and smooth surfaces This

makes the reflected light move in the same direction

16

Mountains and

trees are reflected

in this lake.

17

Look closely at the picture below The drops of water

refract, or bend, light This makes the light change

direction This can change the way things look Each drop of water refracts light from the flower Little pictures of the flower form as the light bends

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Light passes through things at different speeds This

causes the light to refract Light moves more slowly

in water than air The straw in the glass below looks

broken because the water slows down and bends

the light

Refraction can cause light to separate When this

happens you can see a rainbow A rainbow shows the

many colors of light

Why does this straw appear broken?

19

Light is made of many colors When light hits

objects, they absorb some of the light To absorb

means to take in The rest of the light is reflected

Things absorb and reflect different colors of light If something looks white, it is reflecting all the colors of sunlight If something looks black, it is absorbing all the colors of sunlight Absorbed sunlight often turns to heat This is why dark objects feel warm in sunlight

Green light has changed this white chicken to a green chicken.

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What is electrical energy?

Electric Charges

Matter is made up of particles that have electric

charges An electric charge is a small bit of energy

An electric charge can be positive or negative Matter

with mostly negative charges has a negative charge

Matter with mostly positive charges has a positive

charge Matter with the same number of negative and

positive charges has no charge

This balloon has no charge It does not attract any pieces

of paper.

21

Positive and negative charges attract The negative charge moves toward the positive charge You may get a shock when you touch a person If so, negative charges jumped between the two of you

The attraction between opposite charges can make things stick together That’s why paper sometimes sticks to a balloon

The same charges repel each other Objects with the same charge push each other away

This balloon has a charge

It attracts pieces of paper with an opposite charge.

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Electric Currents and Circuits

Electric current is the movement of electrical

energy or electric charge from place to place

Lightning is an electric current that moves in any

direction Electric current must follow a path

to be useful Electric current can make lights and

CD players work The path that a controlled electric

current flows through is an electric circuit Energy

cannot flow if the path, or circuit, is broken Look at

the picture below The switch must be closed for the

electricity to flow

Electricity flows through the circuit to light the light bulb when the switch is closed.

Energy source

Switch

Light

Heat

Sound

How Electrical Energy Changes Form

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We need to make a lot of electricity because we use

it every day We have learned how to change energy into electricity We can change the energy of moving water into electricity We can change the energy of burning coal into electricity We can turn the energy of heat and sunlight into electricity What would modern life be like without electricity?

Light bulb

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Glossary

electric current flows through

energy or electric charge from one place to another

potential energy stored energy

have it travel in a different direction

in matter

Vocabulary

absorb

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)

Chillmaid-Spencer Grant/Photo Researchers, Inc.

ISBN: 0-328-13844-4

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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