Strain The fractional change in configuration is called strain. Strain = Change in the configuration / Original configuration It has no unit and it is a dimensionless quantity. According to the change in configuration, the strain is of three types( 1) Longitudinal strain = Change in length / Original length( 2) Volumetric strain = Change in volume / Original volume
( iii) Shearing strain = Angular displacement of the plane perpendicular to the fixed surface.
Hooke’ s Law Within the limit of elasticity, the stress is proportional to the strain. Stress & infi; Strain or Stress = E * Strain where, E is the modulus of elasticity of the material of the body.
Types of Modulus of Elasticity
1. Young’ s Modulus of Elasticity It is defined as the ratio of normal stress to the longitudinal strain Within the elastic limit. y = Normal stress / Longitudinal strain y = FΔl / Al = Mg Δl / πr 2 l
Its unit is N / m 2 or Pascal and its dimensional formula is [ ML-1 T-2 ]. 2. Bulk Modulus of Elasticity
It is defined as the ratio of normal stress to the volumetric strain within the elastic limit. K = Normal stress / Volumetric strain