A large rock on the top of a mountain has potential energy. If a small amount of energy sets the rock in motion, this potential energy is converted to kinetic energy. The following picture is a large balanced rock in Leslie Gulch in Oregon.

The water stored behind a dam has potential energy, which can be converted to electrical energy. Electrical energy arises from the flow of electric current. This current may force a wire to heat up and emit energy in the form of heat and visible light.  It may pass through a coil and produce a magnetic field, which in turn will cause a motor to run.

Chemical compounds have potential energy in the bonds between atoms. Some chemical reactions release energy in the form of heat. These reactions are called exothermic reactions.  A common example of this is the burning of a fuel such as coal or wood. A battery converts chemical energy into electrical energy when a contact is made between the electrodes. The following heartbreaking picture of the horror of forest fires was taken in the Bitterroot National Forest in Montana on August 6, 2000 by a fire behavior analyst from Fairbanks, Alaska by the name of John McColgan.

The most common type of work experienced in chemical reactions is an increase in the volume of the system. A chemical reaction also does work by moving electrons or atoms.