Types of energy

Many different types of energy exist, but overall they are divided into two different forms of energy: Potential or Kinetic.

Potential energy, E_pot, is the energy an object holds due to its position relative to other objects or to factors like electric charge or internal stress:

• A ball lying on top of a hill has potential energy, because of its position relative to the gravitational pull of the earth.

• A spring that is extended has potential energy, because it is stretched against the stress of the material it is composed of.

Kinetic energy, E_kin, is the energy an object holds due to its motion:

• The ball rolling down the hill has kinetic energy, because it is in motion.