Differentiate between stress and strain

Question

Differentiate between stress and strain?

Accepted Answer

Stress:

The force acting on a unit area at the surface of a body is called stress.

Thus stress = $\frac{Force}{Area}$

Unit: In SI, the unit of stress is newton per square meter $(Nm^{-2})$.

Strain:

A comparison of such a change caused by the stress with the original length, volume, or shape is called strain.

If stress produces a change in the length of an object then the strain is called tensile strain.

Tensile strain = $\frac{(Change in length)}{(Original length)}$

The strain has no units as it is simply a ratio between two similar quantities.