What is strain ? Explain longitudinal strain (`epsi`).

Explanation

If a solid body under external force, its dimension change by three ways: (1) In length (2) in volume and (3) in shape
The fractional changes in dimension of body is known as strain
Longitudinal Strain : The deforming force produces a fractional change in length is known as longitudinal strain.
If the original length Lis of the body and F is the deforming force its change in length is `DeltaL,` then longitudinal strain `epsi _(l) = (DeltaL)/(L)`
If the length increases the corresponding longitudinal strain is called tensile strain and if the length decreases then the corresponding strain is called compressive strain.