The reel shown in figure has radius R and moment of inertia I . One end of the block of mass m is connected to a spring of force constant k , and the other end is fastened to a cord wrapped around the reel. The reel axle and the incline are frictionless. The reel is wound counterclockwise so that the spring strectches a distance d from its unstretched position and the reel is then released from rest. The angular speed of the reel when the spring is again unstretched is. .
