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