dynamics newton s second law kinematics problem

The figure shows a 25-kg uniform disk with radius 300 mm and center of gravity at G. A 6-kg mass is attached to the edge of the disk at A. A spring with spring constant k = 380 N/m is attached to the disk at G. A small motor (not shown) provides a constant clockwise moment of M = 20 N·m to the disk. The system is released from rest with the spring initially compressed by 0.2 m and A positioned vertically above G. Determine the angular velocity of the disk after the disk has rolled through 90 degrees.The disk rolls without slipping. Assume the mass moment of inertia of the mass at A about its own center of gravity to be very small and can be ignored. Attached is the figure.