**Potential energy** Potential energy is energy stored within a physical system. Potential energy exists when there is a restoring force that tends to pull an object back towards some lower energy position.

It is called the potential energy because it has the potential to be converted into other forms of energy (e.g. kinetic energy).

When a path is taken from one point to another the restoring conservative (independence of the path taken from one point to the other) force gives rise to energy. In general, the work done by a conservative force is W = -∆V where ∆V is the change in potential energy due to a force F.

__Example: Hooke's law__ The restoring force in a spring is F = -kx where k is the string stiffness constant and x is the position from where the spring is at equilibrium.

If we stretch the string the work done is:

U = -∫ Fdx

where U is the potential energy and the integral is a sum over infinitesimal small steps along x (dx).

U = -∫ Fdx = -∫ (-kx) dx = + ½kx

^{2} __Source:__ Potential Energy - Wikipedia

http://en.wikipedia.org/wiki/Potential_energy