Voila 3

To illustrate the conservation and conversion of energy, think about a tire swing over a creek. When the tire swing is held in its highest position, it is not moving. It does contain stored energy, however, owing to its position. We refer to the stored energy as potential energy. Other examples of potential energy are the gravitational energy in water behind a dam; the chemical energy in coal, fuel oil, and gasoline, as well as in the fat in your body; and nuclear energy, which is related to the forces binding the nuclei of atoms.

 

The tire swing, when released from its highest position, moves downward. At the bottom straight down, the speed of the tire swing is greatest, and no potential energy remains. At this point, all the swing’s energy is the energy of motion, called kinetic energy.

 

As the tire swings back and forth, the energy continuously changes between the two forms, potential and kinetic. However, with each swing, the tire slows down a little more and goes a little less high because of friction created by the movement of the tire and rope through air and friction at the pivot where the rope is tied to the tree.