Stored Energy in a stretched material
When a material experiences a stretching forceÂ workÂ is done on the material by the applied force. This force causes the atoms of the material to beÂ displacedÂ from their original positions and so they gainÂ internal potentialÂ (orÂ elastic) energy.
It can be shown that the stored energy is given by the following equation:
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â STORED ENERGYÂ =Â Â½ F xÂ Â Â Â Â
(Note:Â FÂ must be inÂ newtonsÂ andÂ xÂ inÂ metresÂ for this equation to give energy inÂ J).
However,Â since F = kx, then if we substitute for F in the above equation we obtain the equation: