Question

a person 0f mass m = 60 kg walks along the radius from the periphery to the center of a circular platform of moment of inertia= 200kgm square and radius r = 3m. the disk is a rotating frictionless with angular velocity= 0.3 rad\s.find the angular velocity of the system when the person is 50 cm from the center. find the change of mechanical energy during the displacement. assuming that the walk takes 2.50s, find the average torque exerted by the person on the platform.