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ENERGY: Part 3 – How does Energy change form?

If you were to ask your friends to give examples of energy, you would probably get many different answers. Some of them might mention the energy in a flame. Others might suggest the energy needed to run a race. Energy occurs in several different forms. Fire has heat and light energy. Fat stored in your body contains chemical energy.

In causing other things to change, energy itself often changes from one form to another. Any change of energy from one form to another is called an energy transformation. Energy transformations take place all around you every day. When a car sits in the sun all day, the solar energy (or light energy from the sun) changes to heat energy. The chemical energy in fireworks’, ingredients change to light, sound and heat energy when they are set off.

During a transformation, such as when light changes to heat, the total amount of energy stays the same – no energy is lost or gained. ONLY THE FORM OF ENERGY CHANGES, NOT THE AMOUNT. Scientists call this idea the Law of Conservation of Energy, and it states three things:

  • Energy cannot be made.
  • Energy cannot be destroyed. It is never “used up.”
  • Energy can just change from one form to another.

Since the earliest times, human beings have changed energy into forms that are useful to them. Early humans learned to change chemical energy to heat and light energy when they learned to make fire. Today, energy transformations are happening around you all the time. You flip up the switch in your home and the lights go on. Electrical energy has changed to light energy. Your toaster converts electrical energy to heat energy. A fan changes electrical energy to mechanical energy. Its motor gets hot. You can also hear it. This means some of the energy has transformed to heat and sound energy. Hydroelectric and wind power plants transform mechanical energy from moving water and air into electrical energy.

Wasted Energy

A car takes the chemical energy in gasoline and converts it into the mechanical energy of its motion. However, not all the chemical energy of the gasoline transforms into mechanical energy. In fact, only a small amount of the chemical energy changes into energy that moves the car. The rest is waste. Some of the fuel’s energy is wasted as sound. Most of the energy is wasted as heat.

Some waste energy is always given off when energy changes from one form to another. Most waste energy is in the form of heat. People who design cars try to make them waste as little energy as possible. These people are called engineers. Engineers are people who take science ideas and put them to practical use.

Fill in the blank

Complete each statement using a term or terms from the list below. Write your answers in the spaces provided. Some answers may be used more than once.

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heat

mechanical

nuclear

change

chemical

light

sound

created

destroyed

transformations

electrical

move

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  1. Energy is the ability to make something ______.
  2. The main forms of energy are ______, ______, ______, ______, ______, ______, and ______,
  3. The idea that Energy cannot be ______or ______but can only transform from one form to another is called the Law of Energy Conservation.
  4. The energy of moving things is called ______energy.
  5. Energy changes are called ______.
  6. Food has ______energy
  7. The body changes chemical energy into ______and ______energy.
  8. ______is the ability to do work and change matter.
  9. Motors sometimes give off wasted energy in the forms of ______and ______energy.
  10. The useful energy a motor gives is ______energy.

True or False

In the space provided, write “T” if the sentence is true. Write “F” if the sentence is false.

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______1. Heat is a form of energy.

______2. Heat is the only form of energy.

______3. Heat is sometimes useful.

______4. Heat energy is always useful.

______5. Energy can change from one form to another.

______6. Energy conversions always give off heat.

______7. Heat energy can change to mechanical energy.

______8. Mechanical energy can change to heat energy.

______9. Energy changes are called transformations.

______10. Energy changes are called conservation.

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Matching

Match each term in Column A with its description in Column B. Write the correct letter in the space provided.

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Column A

_____ 1. energy

_____ 2. wound-up spring

_____ 3. transformations

_____ 4. mechanical energy

_____ 5. battery

Column B

a) has stored mechanical energy

b) has stored chemical energy

c) energy of moving things

d) the ability to make things move

e) energy changes

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Label the picture

Study the following pictures. For each picture (or set of pictures) tell what kind of energy transformation is shown.

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