Rigidity Modulus and Bulk Modulus

Rigidity Modulus

It is a measure of identifying the strength of your body in protecting its a shape. In this case, we fix the lower surface of the body and apply the horizontal force on the upper surface of the body. In this process,the upper layer shifts when compared with the lower layer by an angle. The stress developed here called shearing stress and the corresponding strain is called shearing strain. Here strain is defined as the ratio of the shift of the upper layer when compared with the lower layer to the perpendicular distance between the two layers.

When the rigidity modulus of a given material is high,then we can say that the material is good in protecting its own shape. No material in the nature is perfectly rigid. Among all the available materials in the nature ,diamond is the best possible material who is very strong in protecting against the applied forces.

Bulk modulus

It is defined as the ratio of bulk stress acting on a body to the bulk strain. If the forces acting on a body simultaneously from all the direction the corresponding force per unit area is called bulk stress. Change in the volume of the body to its original volume with respect to the bulk stress is called bulk strain.

We generally apply the force from the outside the body therefore the to change the volume, particularly it tended to decrease the volume. That is why the bulk strain is shown with a negative term.