Question

A solid cylinder is sliding on a smooth horizontal surface with velocity $v_0$ without rotation. It enters on the rough surface. After that it has travelled some distance, select the correct statement :

• A. Friction force increases its translational kinetic energy.
• B. Friction force increases its rotational kinetic energy.
• C. Friction force increases its total mechanical energy.
• D. Friction force increases its angular momentum about an axis passing through point of contact of the cylinder and the surface.

Answer 1

Answer: (B)

Friction force increases its rotational kinetic energy.

The friction force will reduce $v_0$ hence translational K.E.
The friction force will increase $\omega$ and hence increase its rotational kinetic energy.
There is no torque about the line of contact, angular momentum will remain constant.
The frictional force will decrease the mechanical energy.