Question

If ring and sphere both of same mass are rotated then which of them will come to rest first ? And which is easy to rotate? And the relation of moment of inertia with rotation?

Answer 1

Sphere will come to rest first,Becausethe mass is concentrated towards the “rim” it has a higher moment of inertia, meaning it is harder to accelerate the ring than the sphere from rest - and conversely, it is harder to stop the ring once you’ve already invested the energy to accelerate both to the same velocity.
Its the sphere which is easy to rotate