If there is no external force acting on a nonrigid body, which of the followhng quantities must remain constant?

Options

A. Moment of inertia of the body
B. Angular momentum of the body
C. Linear momentum of the body
D. Kinetic energy of the body

Answer

A, D

Explanation

Since the body is non-rigid hence its mass distribution around the axis of rotation may change and it will change the moment of inertia. So option (a) is correct. Where there are no external forces acting on the system then definitely there is no external torque hence linear momentum as well as angular momentum will remain constant hence options (b) and (c) are correct. Internal forces can change kinetic energy of the system hence option (d) is also correct.