A 4.80 kg disk is free to rotate about an axis during its center (+z); the plane of the disk is horizontal and the radius of the disk is 36.0cm. It initially rotates with an angular velocity of (18.0 rev/s, -z). Due to torques acting on the disk, the angular velocity is (6.00 rev/s, -z) after the disk has turned during 120 revolutions. Decide (a) the angular acceleration through this time; (b) the elapsed time; and (c) the linear velocity of a point on the edge of the disk after the disk turned during 60 revolutions.