Potential Energy

In this chapter we continue the discussion of energy that we began in Chapter 7. To do so, we define a second form of energy: potential energyis energy that can be associated with the configuration (or arrangement) of a system of objects that exert forces on one another. If the configuration of the system changes, then the potential energy of the system can also change.

One type of potential energy is the gravitational potential energythat is associated with the state of separation between objects, which attract one another via the gravitational force. For example, when Andrey Chemerkin lifted the record-breaking weights above his head in the 1996 Olympics, he increased the separation between the weights and Earth. The work his force did changed the gravitational potential energy of the weights-Earth system because it changed the configuration of the system - that is, the force shifted the relative locations of the weights and Earth.

Another type of potential energy is elastic potential energy,which is associated with the state of compression or extension of an elastic (springlike) object. If you compress or extend a spring, you do work to change the relative locations of the coils within the spring. The result of the work done by your force is an increase in the elastic potential energy of the spring.

The idea of potential energy can be an enormously powerful tool in understanding situations involving the motion of an object. With it we can, in fact, easily solve problems that would require careful computer programming if we used only the ideas of earlier chapters.