Q: A circular platform is mounted on a frictionless vertical axle. Its radius R = 2 m and its moment of inertia about the axis is 200 kgm^2. If is initially at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at the sped of 1 m/s relative to the ground. Time taken by the man to complete one revolution is
(a) π s
(b) 3π/2 s
(c)2π s
(d) π/2 s
Ans: (c)