Stress

							Card # 15 Stress
When a deforming force is applied on a body it gets deformed. Then a restoring force starts acting, which tries to bring the body back to its original shape or size, it opposes the external force. This internal restoring force acting on unit area of cross section of a body is called stress. Within the elastic limit deforming force = restoring force If area of cross section = A External deforming force = F Then restoring force = F Stress =

F A N m2
MLT −2 = ML−1T −2 L2

Unit of stress =

Dimensional formula =

Stress
If the deforming force is applied normally at the surface of a body, the applied force per unit area is called normal stress. When the force acts tangentially (parallel to the surface) over an area, body gets shared through a certain angle. Body is subject to a uniform and equal force from all sides.

L = Original length l = Change in length Final length = L + l A= Area of cross section Force applied = F Tensile Stress =

L = Original length l = Change in length Final length = L - l A= Area of cross section Force applied = F Compressive Stress =

F A

F A