Question

a thin ring of mass 2 kg is rolling then is friction necessary

Answer 1

yes friction is necessary for rolling

Answer 2

Rotational motion problems in JEE invariably involve the concept of rolling and rolling without slipping. Rolling is a very easy concept to understand and this post is dedicated to understanding rolling and rolling without slipping. After reading through this lesson you will be able to solve qualitative and quantitative problems on rolling easily.

Consider a wheel standing upright on a horizontal surface. If we apply an external force F on the wheel it can exhibit two kinds of motion.

First, in which the wheel skids and rotates as in the figure below (similar to what happens when you apply brakes to your bike – the wheel drags and stops ).

and secondly when the wheel exhibits only circular motion and does not skid on the surface. This is called rolling without slipping and since there is not no slipping (skidding) the net velocity of the bottom most point or the contact point of the wheel should be zero such that