A pulley of radius 2 m is rotated about its axis by a force F = (20t – 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg-m2 the number of rotations made by the pulley before its direction of motion is reversed, is:
(a) more than 3 but less than 6
(b) more than 6 but less than 9
(c) more than 9
(d) less than 3
