Question

A solid homogeneous sphere is moving on a rough horizontal surface, partly rolling and partly sliding. During the king of motion of the sphere.
A. total kinetic energy is conserved
B. angular momentum of the sphere about the point of contact with the plane is conserved
C. only the rotational kinetic energy about centre of mass is conserved
D. angular momentum about centre of mass is conserved

Answer 1

Correct Answer - B
Since, the sphere is sliding, maximum force of friction will act passing through, the bottommost point. Torque of this force about point of contact is zero. Hence, angular momentum will remain conserved about the point of contact and not about the centre of mass. About centre of mass torque of friction will not be zero.