Explain what is stress ? Write its unit and dimensional formula.

Explanation

When forces are applied on a body in such a manner that the body is still in static equilibrium it is deformed to a small or large extent.
Deformation depending upon the nature of the material of the body and the magnitude of the deforming force.
The deformation may not be noticeable visually in many materials but it is there when a body is subjected to a deforming force, a restoring force is developed in the body.
This restoring force is equal in magnitude but opposite in the direction to the applied force.
The restoring force per unit area is known as stress.
If F is the force applied and A is the area of cross section of the body,
Magnitude of stress `=F/A` Its SI unit is `Nm^(-2)` or Pascal (Pa).
Its dimensional formula is (`ML^(-1)T^(-2)`).