Unit 3 Energy 5.1

Energy is defined in science as the ability to move matter or change matter in some other way. Energy can also be defined as the ability to do work. When work is done, energy is transferred from one object to another.

Because energy is the ability to do work, it is expressed in the same unit that is used for work. The SI unit for both work and energy is the joule (J), or Newton ∙ meter (N ∙ m).

• If you think about different sources of energy—such as batteries and the sun—you probably realize that energy can take different forms.

• Energy stored in food, is an example of chemical energy. Other forms of energy include electrical, thermal, light, and sound energy.

• The different forms of energy can also be classified as kinetic energy, potential energy, or a combination of the two. Kinetic energy is the energy of moving matter. Potential energy is energy that is stored in matter.