Elastic potential energy is the energy stored in elastic materials as the result of their stretching or compressing. Elastic potential energy can be stored in rubber bands, bungee chords, trampolines, springs, an arrow drawn into a bow, etc. The amount of elastic potential energy stored in such a device is related to the amount of stretch of the device - the more stretch, the more stored energy.

If a spring is not stretched or compressed, then there is no elastic potential energy stored in it. The spring is said to be at its equilibrium position. The equilibrium position is the position that the spring naturally assumes when there is no force applied to it. In terms of potential energy, the equilibrium position could be called the zero-potential energy position. There is a special equation for springs which relates the amount of elastic potential energy to the amount of stretch (or compression) and the spring constant.

 Definition provided by Physics Classroom

 Example Problem 

If the force to stretch a spring is given as F = (100 N/m)x then what is the potential energy of the spring if it is stretched 2 meters from rest? 

Solution

Use PE = 1/2 kx^2  

 PE = Potential Energy 

k = Spring Constant 

x = Compression or stretch of the spring 

PE = 1/2 kx^2 

PE = 1/2(100 N/m)(2m)^2 

PE = 200 J 

 Example Provided by Batesville