This is the
energy objects possess because of their position.
Example: A stone poised at the top of a cliff.
Imagine a force that is continuously exerted
on a body; for example, the gravitational interaction producing the body's weight.
To move upward against that downward pull requires the application of a
counter-force (provided by muscles) and the doing of work.
A body raised in a gravitational field still experiences a downward force while held up
there at rest. When let loose, it will fall; it will be driven back down toward
where it came from and kinetic energy will be imparted to it in the process. Work
done on the system is ultimately converted into KE and follows the law
of conservation of energy.
But what if the system was held motionless,
high in the gravitational field. KE is not liberated until the system is released.
Although it is possible to do work on a system and not have immediately have
the work appear as KE. Yet the potential for generating that energy is there because
of the ever-present force. Energy is stored in the system of interacting objects,
waiting to let loose. This retrievable stored energy, energy by virtue of position
or configuration in relation to a force, is known as potential energy (PE).
The change in the potential energy of a system
incurred in moving from one point to another equals the work done in overcoming the
interaction that stores the energy. PE exists only in relation to systems of
interacting objects. |
