Elastic potential energy

When a spring is stretched, work is done, which means some energy was transferred.

This energy has to go somewhere, and so it’s transferred into the elastic potential energy store of the object.

When the tension is removed from the spring, energy is transferred from the elastic potential store, and into kinetic energy.

• If the spring has plastic behaviour, it will not fully return to its original shape when the force is removed, as not all the elastic potential energy is transferred back into kinetic energy.
• If the spring has fully elastic behaviour, it will return to its original shape because all its elastic potential energy is converted back into kinetic energy.

E=\frac12k\Delta L^2

• E is the energy transferred, in joules (J)
• k is the spring constant, in newtons per metre (Nm^{-1})
• \Delta L is the extension of the spring, in metre (m)

E=\frac12F\Delta L

• E is the energy transferred, in joules (J)
• F is the force applied, in newtons (N)
• \Delta L is the extension of the spring, in metre (m)