Consider that a stone of mass M is revolved along a circular path by tying it to a thread of length 'l'.
Moment of inertia of the stone, I = Ml2
Suppose that a torque τ is applied to produce an angular acceleration α. then
It follows that to produce the same amount of angular acceleration; the larger torque is required, When longer string is used to revolve the stone of given mass. Hence, it is more difficult to revolve the stone by tying it to a longer string.
