1.1.5 Elastic Potential Energy

When we stretch a spring, we're applying a force to change the length of the spring. Applying a force like this is called doing work. We're putting energy in to stretch the spring. The stretched spring is storing this energy and we call that elastic potential energy.

Where Ee, is the elastic potential energy, in joules, J, k is the spring constant, in newtons per metre, N/m and e is extension in metres, m.

• X-axis: Extension (m)
• Y-axis: Force applied (N)
• The graph shows a linear relationship until it reaches the limit of proportionality.

Extension ∝ Force

Limit of proportionality: If too great a force is applied, the spring will not return to its original length.