A drum of  radius  and mass , rolls  down without slipping along an inclined plane of angle . The frictional force
a)	Converts translational energy to rotational energy	b)	Dissipates energy as heat	c)	Decreases the rotational motion	d)	Decreases the rotational and translational motion

(a)

When a body rolls down without slipping along an inclined plane of inclination , it rotates about a horizontal axis through its centre of mass and also its centre of mass moves. Therefore, rolling motion may be regarded as a rotational motion about an axis through its centre of mass plus a translational motion of the centre of mass. As it rolls down, it suffers loss in gravitational potential energy provided translational energy due to frictional force is converted into rotational energy.