Elasticity in Physics

Every solid is a spring, just a very stiff one. Pull it and it lengthens, twist it and it distorts, squeeze it and it shrinks, and up to a limit it returns to shape afterwards. To compare materials fairly, the force is divided by the area it acts over so that a thick bar and a thin wire become comparable, and the distortion is divided by the original size for the same reason. What is left is a pure property of the material, and that is what the three moduli on this page measure. The blocks give stress and strain in each of the three ways a solid can be deformed, then the modulus and the deformation each one predicts.