Energy is found in many forms. Coal is a form of energy---We burn natural gas so we can cook our food which we eat to give us energy. Sunlight is a form of energy---Plants absorb the sun's energy in order to grow. All forms of energy fall into one of two categories: potential energy or kinetic energy. While there is only one kind of kinetic energy, there are three common kinds of potential energy – nuclear, electric, and gravitational.
POTENTIAL ENERGY
Potential energy is stored energy. A roller coaster sitting at the top of the track has potential energy. Coal has potential energy because we need to do something to it in order to access its energy.
![](/sites/eli.lehigh.edu/files/coaster_top.jpg)
KINETIC ENERGY
Kinetic energy is the energy of motion. A roller coaster zooming down the track has kinetic energy. Sunlight has kinetic energy because light waves are constantly in motion and can be absorbed.
![](/sites/eli.lehigh.edu/files/coaster_down.jpg)