When a spring is stretched or compressed, energy is transfere. The force does work to change the shape of the spring, transferring energy to its elastic potential energy store. If the spring is elastically deformed, the work done by the force on the spring and the elastic potential energy stored are equal.

Elastic potential energy (or work done) can be calculated by using the following equation:

• $Ee$ is the elastic potential energy of the spring in Joules (J)
• $k$ is the spring constant in Newtons per metre (N/m)
• $e$ is the extension (or compression) in metres (m).

This equation is only valid for elastic objects up to the limit of proportionality.