 Welcome back MechanicalEI, did you know that strain energy is the reason why your rubber band gun works quickly to hit your friend at the right place? This makes us wonder what is strain energy? Before we jump in, check the previous part of the series to learn about what torsion is. Now, strain energy is the energy stored by a system undergoing deformation. For linearly elastic materials, strain energy U is given as half the product of volume V, stress, sigma and strain epsilon. Resilience is the ability of a material to absorb energy when it is deformed elastically and release that energy when unloading. It is also defined as the area under the linear portion of a stress-strain curve. Proof resilience is defined as the maximum energy that can be absorbed up to the elastic limit without creating a permanent distortion. Sector body which is subjected to tensile load increasing gradually up to its elastic limit from value 0 to value p and therefore deformation or extension of the body is also increasing from 0 to x. The strain energy stored in such a body is given by the product of stress squared and volume divided by twice the Young's modulus. Modulus of resilience is defined as the maximum energy that can be absorbed per unit volume without creating a permanent distortion. It can be calculated by integrating the stress-strain curve from 0 to the elastic limit. Hence, we first saw what strain energy and resilience is and then went on to see how gradually applied load results in stored strain energy. So here are the top mechanical years of our last videos. In the next episode of Mechanical Year, find out what impact loads are.