# Elastic energy

Elastic energy is potential energy related to elastic force, stored in the deformation of a material (compression or stretching) or a physical system (distortion of volume or shape) exhibiting a restorative force. This also means that elastic potential energy is zero in objects that have not been stretched or compressed. The elastic potential energy equation is used in calculations of positions of mechanical equilibrium. The energy is potential as it will be converted into the second form of energy, such as kinetic.

$U=\dfrac{1}{2}k\Delta x^2$

where $$k$$ is the elastic constant of the spring while $$\Delta x$$ is the distance of stretching/compression. Since this is a particular type of energy, elastic potential energy is measured in joules (J).

## Properties of elastic potential energy

The elastic potential energy is directly proportional to both the elastic constant $$k$$ and the square of the spring stretching $$x$$; so the potential elastic energy cannot be negative. The energy stored in a spring depends on the:

• the shape of the spring;
• how much the spring is deformed (stretched or compressed);
• materialâ€™s elasticity of the spring;
• the value of the spring constant, which defines the amount of force required to deform a spring by a certain length (the work done on the spring).