Tensile and Compressive Forces

When a pair of equal and opposite forces acts on an object, they can change its shape. Forces that stretch an object and produce an extension are called tensile forces. Forces that squash an object and shorten it are called compressive forces.At least two forces are needed to deform an object. A single force would simply make it accelerate. A wire hanging from a support with a mass on the end is stretched because the support pulls up while the weight pulls down.The change in length caused by tensile forces is called the extension. The change caused by compressive forces is called the compression. Both are measured from the original length.If the object returns to its original shape when the forces are removed, the deformation is elastic. If it stays permanently deformed, the deformation is plastic.