A solid cylinder is rolling down a rough inclined plane of inclination . Then [2006]
(3, 4)

The sliding friction acts in the opposite direction of to oppose the relative motion. Because of frictional force the cylinder rolls.
Hence frictional force aids rotation but hinders translational motion.
Applying along the direction of inclined plane,
where is acceleration of centre of mass of the cylinder
Clearly, if is reduced, frictional force is reduced.