Question

A solid homogeneous sphere is moving on a rough horizontal surface, partially sliding. During this kind of motion of sphere

• A. Total kinetic energy is conserved
• B. Angular momentum of the sphere about the point of contact is conserved
• C. Only the rotational kinetic energy about the centre of mass is conserved
• D. Angular momentum about the centre of mass is conserved

Answer 1

The correct option is B Angular momentum of the sphere about the point of contact is conserved

Net torque about the point A is Zero.

Now, $\frac{d{L}_A}{dt}={\tau }_A=0$

Thus $L_A$ is conserved.