Forms of energy

Physical Sciences
Standards
Preview
Standard Set 1. Physical Sciences
1. Energy and matter have multiple
forms and can be changed from
one form to another. As a basis for
understanding this concept:
1.a. Students know energy comes from
the Sun to Earth in the form of light.

1.c. Students know machines and
living things convert stored energy to
motion and heat.
1.d. Students know energy can be
carried from one place to another by
waves, such as water waves and sound
waves, by electric current, and by
moving objects.

1.b. Students know sources of stored
energy take many forms, such as food,
fuel, and batteries.

Genre

Nonfiction

Comprehension Skill

Main Idea and Details •

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•
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Text Features

Captions
Charts
Diagram
Glossary

Science Content

Forms and
Properties of
Energy

Scott Foresman Science 3.1

ISBN 0-328-23518-0

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by Lillian Duggan


Vocabulary
compression wave
electricity
energy
energy of motion

friction
stored energy

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ISBN: 0-328-23518-0
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by Lillian Duggan


Energy Sources
Energy is the ability to do work. You do work when
you make something move. Carrying your books and
walking to school are ways of doing work. Without
energy, things cannot move, stretch, or grow. Physical
and chemical changes can only happen with energy.
The Sun provides most of the energy used on Earth.
This energy reaches Earth as light and heat. It warms
Earth to a temperature that living things need.

The Sun’s energy reaches Earth
as heat and light. This energy
allows living things to grow.

Using Stored Energy
The energy your body uses does not come directly
from the Sun. It comes from stored energy in the food
you eat. When digested food reaches your body parts,
this energy is released. Stored energy is also found in
batteries, as well as in fuels such as gasoline.

Using Energy from Batteries
Stored energy can be used up. Suppose you have a
toy car that runs on a battery. When the car is turned on,
the chemical energy in the battery changes into energy
of motion. When you play with the car, the energy gets
used up. Eventually, the battery runs out of energy and
the car stops running.
A battery-operated toy car
changes chemical energy
into energy of motion.

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Getting Energy from Fuel

Getting Energy from Food

When food is cooked on a charcoal grill, the burning
charcoal gives off heat energy, which cooks the food, and
light energy. The charcoal is a fuel. Coal, oil, natural gas,
and gasoline are fuels. When a fuel burns, its chemicals
change. Stored energy is released. The stored energy
becomes heat and light energy.
Oil and natural gas are used to heat homes. The fuel is
burned in a furnace. Burning the fuel causes heat energy
to be released. The heat energy warms the air inside the
house. Heat energy can also be used to cook food.

Your body needs energy to grow, play, learn, and stay
at the right temperature. You get that energy from food.
Food has stored energy.
When you eat, your body breaks down food into
different substances. Some of the substances are carried
to your muscles by your blood. Your muscles change the
substances into energy of motion and heat energy. You
use the energy of motion to run and play. The energy of
heat is used to keep your body warm.

The chemicals in charcoal
release stored energy when
the charcoal is burned.

Energy from food allows
these athletes to run and
kick the soccer ball.

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Energy’s Changing
Forms
Energy constantly changes forms. These changes
happen in living and nonliving things.
A moving object has energy of motion. It carries
its energy of motion as it moves. An object that is not
moving does not have energy of motion.
Some energy changes are caused by machines. A
toaster changes electrical energy into heat energy.
The car’s engine changes the
chemical energy in gasoline
to energy of motion.

Forms of Energy
Chemical
Chemical energy holds together
particles of matter, including those
that make up food. It gives our bodies
energy.

Motion
Energy of motion makes objects
move. Swinging changes stored
energy into energy of motion.

Electrical
Electrical energy moves through
wires made of certain metals. It
provides power to run electrical
appliances in homes.

Light
Light energy from the Sun is used
by plants to make food. Other forms
of energy are changed into light to
help people see.
Thermal
Thermal energy makes particles of
matter move faster. We feel thermal
energy as heat.

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Transferring Energy of Motion

Friction

A moving object has energy of motion. If it hits
another object, the energy is transferred, or moved, to the
other object. The second object starts to move, but the
first object slows down or even stops.
Suppose you are playing with a set of toy trains on

a track. You push one train and let go. It bumps into
another train. The second train begins to move, while the
first train gradually stops moving. The energy of motion
of the first train is transferred to the second train. The
total amount of energy does not change.

When a moving object touches another object, some
energy of motion changes into heat energy. Friction
causes this change. It reduces a moving object’s energy of
motion. This causes the object to slow down.
Suppose you are riding a bicycle. Your bike will keep
moving for a while after you have stopped pedaling.
But soon the bike will slow down and stop. The contact
between the tires and the road causes friction. Some of
the bike’s energy of motion becomes heat.

When the white ball hits the yellow
ball, its energy of motion is transferred.

To overcome the force of friction,
you must keep pedaling.

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Ways that Energy
Moves
Ocean waves carry a great deal of energy. As energy is

moving through ocean water, the energy moves forward.
The water itself moves up and down.
When you shake sand out of a beach towel, the
towel moves up and down as waves pass through it.
But the towel does not move forward. In a water
wave, the water moves up and down. But it does not
move forward.

Making Water Waves
If you visit a lake or pond, you can see how energy
moves in water waves. Find an area where the water is
still and there is no wind. Gently place two lightweight
sticks on the water. Then toss a rock in the water near
the sticks. The rock will create waves in the water. As the
waves move near the sticks, the sticks will move up and
down. They might also move from side to side a little.
But notice that the sticks do not leave the spot where you
placed them.
The waves move the water in
this pond up and down, but not
from one place to another.

The more energy a wave
has, the larger it is.

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How Sound Waves Move

How We Hear Sound

Sound waves carry energy produced by vibrations.
When you knock on a door, it vibrates, causing the
surrounding air to vibrate. These vibrations push the
air particles together. Then the air particles move apart.
The back-and-forth movement of particles makes a kind
of wave called a compression wave. Sound waves are
compression waves.

The sound waves produced by a knock on the door or
the chirping of a bird quickly reach your eardrum. Your
eardrum is a thin layer of skin inside your ear. Sound
waves cause your eardrum to vibrate. Small bones next
to your eardrum then begin to vibrate as well. Then the
sound energy is changed into another kind of signal,
which travels to your brain. The bird or the door causes
these changes without actually touching your ear.

The spring’s parts are pushed
together and then move apart as
energy flows through it. Sound
waves travel in a similar way.

When a bird chirps, its
throat and the air around
it vibrate. You hear the
vibrations as sound.

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The parts of your inner
ear pick up sound waves,
allowing you to hear.

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How Earthquake Waves Move
Look at the picture below. It shows earthquake waves
passing through the ground. In real life, you cannot see
earthquake waves. But like ocean waves, earthquake
waves have lots of energy. This energy can cause damage.
Earthquakes are caused by sudden movements of
Earth’s crust. These movements cause vibrations in the
ground. The vibrations travel in waves. They can cause
buildings to fall and roads to crumble.

When an earthquake hits, it
releases lots of energy. The energy
gets carried by earthquake waves.

Earthquakes cause three different kinds of waves.
Therefore, the energy of earthquakes travels in three
different ways. One kind of earthquake wave is similar to
a sound wave. It pushes on the ground as it travels. The
ground then moves back. Another kind is like a water
wave. It causes the ground to shake up and down. And

the third kind shakes the ground from side to side.
Earthquakes cause the greatest damage to buildings
closest to the starting point. The waves gradually lose
energy as they travel. But they can be felt hundreds of
kilometers away from where they begin.
An earthquake released
huge waves of energy that
damaged these homes.

earthquake
waves

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Electricity in Our Lives
Your alarm clock tells you it is time to start your day.
You use the toaster to make breakfast. You study during
the evening by the light of a lamp. Throughout your
entire day, you are using electricity, or electrical energy
that can flow as a charge through a wire.

Electrical energy is made in power plants. Power
plants use fossil fuels, water, wind, or the heat from
nuclear fuel to make electrical energy. The energy is
carried in wires as electricity to your home. Moving
electricity is called electric current. After the electricity
reaches your home, it is changed into the energy of heat,

light, and motion. The type of energy that electricity
becomes depends on the kind of machine or appliance
that uses it.

Transmission Wires
Electricity flows through
wires. The wires connect the
power plant to your home.

Power Source
Electrical energy
is made in a
power plant.

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Power Destination
Electricity flows through wires to
electrical outlets in your home.
Electricity flows into an appliance
after the appliance is plugged
into an outlet.

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Ways We Use Electricity
If you have been camping, you know what it is like to
use only a small amount of electricity. Without electrical
wires and outlets, television sets, refrigerators, and hair

dryers do not work. These things change electrical
energy into a form people can use. They allow us to get
information, keep our food cool, and dry our hair.
Humans have spent a lot of time and money
developing ways to make electricity. We use the energy
of moving water and the heat of burning fuel to generate
electricity. Nuclear power stations change the heat made
by special fuel into electricity. Even the energy in sunlight
and wind can be used to produce electricity.
Campers often have to get
by with little electricity.

Sources of Electrical Power
These solar cells change sunlight energy
into electrical power.

Coal is burned to produce heat energy at
this electric power plant. The heat energy
is changed into electrical power.

The energy of moving water is used to
produce electricity at this power station.

Nuclear energy is used to produce
electrical power at this plant.

These wind turbines change wind energy
into electricity.

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What did you learn?

Glossary
compression wave

1. Where does the energy your body uses come from?

a wave that carries energy by
squeezing particles together
and then letting them spread
apart

electricity

electrical energy that moves
through wires

energy

the ability to do work; ability to
make things move, stretch, or
grow; or cause change

energy of motion

the energy carried by moving

objects

friction

what changes energy of motion
into heat energy

stored energy

energy in food, fuel, and
batteries that can be changed
to motion, light, or heat

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2. What happens when a fuel burns?
3. How does energy of motion get transferred?
4.

Write a paragraph that
describes what friction is and give an example of how it
works. Include a topic sentence and simple supporting
facts and details.

5.

Main Idea and Details What is the main idea of
page 15? What details support it?