For a perfectly rigid body

Young's modulus of a perfectly rigid body is

The modulus of elasticity of a perfectly rigid body is

The bulk modulus of a perfectly rigid body is

What will be the speed of sound in a perfectly rigid rod?

Does a body rotating about a fixed axis have to be perfectly rigid for all points on the body to have the same angular velocity and the same angular acceleration ?Explain.

Statement-1: Young's modulus for a perfectly plastic body is zero Statement-2: For a perfectly plastic body, restoring force is zero.

For a perfectly black body, its abosrpitve power is