Forms of Energy
Besides potential and kinetic energy, scientists also classify energy into other forms such as: solar energy which is either light or heat, chemical energy, mechanical energy, electric energy, sound energy, or thermal energy.
Solar energy – energy that comes from the sun as light or heat. Light – radiation that we see. (the flame of a candle that you see) Heat – radiation that we feel. (the flame of a candle that you see)
Energy from the sun travels as radiation. The sun produces several kinds of radiation: light, heat, and radio waves. How does solar energy help us? What would happen if we did not have solar energy?
Chemical energy – energy that is released through a chemical reaction.
When it is not being used, chemical energy is potential energy. A chemical reaction is needed to change this potential energy into kinetic energy.
Many substances release energy in this way. Can you think of some examples?
Burning is a chemical reaction that releases energy. If you set a burning candle under a dry twig, what will happen? If you set a burning candle under an iron bar, what will happen? What does this tell you about the chemical energy stored in different materials?
Mechanical energy – the combination of all the potential and kinetic energy that something has.
The windup toy in the photo has a key attached to a spring.
When you turn the key, you wind up, or tighten, the spring. What kind of energy is this? What happens when the key is released?
What is the toy’s kinetic energy? Does the toy still have potential energy as it is moving?
Electric energy – the energy that comes from an electric current; also known as electricity.
Lay your head down on your desk, pretend you are at home and a thunderstorm comes and knocks out your power. You are now in a blackout. What electrical inconveniences do you have?
What kind of energy does a hand- held video game use for power? What do you have to do to a hand- held video gam in order for it to work? What kind of energy comes out of the batteries?
Sound energy – energy in the form of vibrations that travel through matter
When you speak, sound energy from your voice meets air molecules and starts them vibrating. They, in turn, make molecules next to them vibrate, and those make others vibrate.
That’s why our voice can be heard anywhere in the room. Suppose I’m speaking loud enough to be heard in the hallway, even though the door is closed. What happens when the air molecules next to the door start vibrating?
If you place you hands on the radio or television, you can feel the sound vibrations. Some people with hearing disabilities have been able to become dancers by feeling the vibrations of the music through their feet.
Thermal energy – energy associated with temperature; heat energy
Remember that all matter is made up of tiny particles that are always moving. Since they move, they have kinetic energy; also known as thermal energy. The faster the particles move, the more thermal energy the matter has.
Can you give some examples of thermal energy?
Law of conservation of energy – energy can never be made or destroyed, but it can change forms.
Often, one form of energy changes into another form. The batteries in a flashlight contain chemical energy, but the flashlight bulb gives off light. Where does the light come from?
The batteries’ chemical energy changes into electric energy. Then the bulb in the flashlight changes the electric energy into light energy.