Question

What are stress and strain?

Answer 1

Stress: When we try to deform anybody by applying any force, due to an elasticity of a reaction force is created in the body. This reaction force tries to regain the body's previous shape against the applied external force. This reaction force per unit area is known as stress.

Strain: Due to the effect of externally applied force, there is relative displacement between the various parts of the body. Thus the body changes its shape or volume. This deformation is known as strain.

$stress=\frac{F}{A}$

$strain=\frac{△l}{l}$[Here we are considering longitudinal strain]