Elasticity:

A body can be deformed by applying the appropriate force on it. After removing force, if the body regains the original shape of it then it is perfectly elastic and this property is called as elasticity. The property of a substance which makes it possible to change its volume, length, or shape in direct response to a force and to recover its original form upon the removal of a force. This restoring force is proportional to the amount of stretch, as described by Hooke's Law. Hooke's law states that, within the elastic limit stress developed in the body is proportional to the strain produced in it. The maximum stress up to which a body exhibits the property of elasticity is called as elastic limit or the limit of elasticity. The stress is restoring or recovering force per unit area set up inside the body. It is deforming force applied per unit area of the body. The 3 types of stress are: shearing stress, longitudinal stress, volume stress. Strain is the change in dimension of the body because of the deforming force. It can be measured by the ratio of change in dimension to the original dimension. The 3 types of strain are shearing strain, linear strain, and volume strain. There are 3 types of moduli of elasticity corresponding to 3 types of strains. They are Young's modulus of elasticity corresponding to the linear strain or longitudinal strain, Rigidity modulus or shear modulus corresponding to the shearing strain, and Bulk modulus or volume modulus corresponding to the volume strain. Young's modulus of elasticity is, within the elastic limit, ratio of longitudinal stress to longitudinal strain and can be denoted by Y. Rigidity modulus is, within elastic limit, the ratio of tangential stress to shearing strain and can be denoted by n. Bulk modulus is, within the elastic limit of a body, ratio of the volume stress to the volume strain and can be denoted by K.