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How Does Energy Work?
You have learned that energy is the ability to do work. You have also learned that energy comes in many forms. Each form of energy is either kinetic or potential. Kinetic energy is the energy of something moving, such as waves, rays, objects, electrons, atoms, molecules, and substances. So blowing wind is kinetic energy. It is also motion or mechanical energy. Potential energy is stored energy. So a battery has potential energy as well as chemical energy.
One very important thing about energy is that it cannot be created or destroyed. So when we use energy, it does not disappear. It just changes from one form of energy to another. An example is when a car engine burns gasoline. The engine changes the chemical energy of the gasoline into motion energy. The motion energy makes the car run. Some of the chemical energy is also changed into thermal energy. That is why a car engine heats up. The chemical energy from the gasoline has been changed to motion energy and thermal energy.
When energy changes from one form to another, we call it energy transformation. Here are some examples of energy transformations and their uses:
• A television changes electrical energy into sound and light energy. As a result, you can see and hear the television shows.
• A flashlight battery changes chemical energy into light energy. As a result, you can use the flashlight to see in the dark.
• A phone changes sound energy from your voice into electrical energy. This electrical energy is then changed back into sound energy. As a result, the person on the other end of the phone can hear what you said.
• Solar panels change sunlight into electric energy.
Energy transformations produce useful energy (energy that does work). They also produce wasted energy (usually as heat or sound). Most energy transformations are not very efficient. This means they produce a lot of wasted energy. For example, your body changes the chemical energy in food to motion energy. This gives you the energy to move, breathe, and think. But your body is not very efficient at converting food into useful energy. Your body is less than 5 percent efficient most of the time. The rest of the energy is lost as heat.
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1. Match the definition to the correct term.
the energy of something moving
2. Energy cannot be created or destroyed.CorrectIncorrect
3. Fill in the blank using information from the text.
When energy changes from one form to another, we call it .
4. What kind of energy is blowing wind?CorrectIncorrect
5. Energy transformations only produce useful energy.CorrectIncorrect
6. Fill in the blanks using information from the text.
Your body changes the energy in food to energy.