Two identical disks are connected by an elastic shaft of stiffness \(K\). The moment of inertia of each disk with respect to the axis of the shaft is \(J\). The system is at rest when a constant moment \(M\) is applied instantaneously to one of the disks. Determine the motion of the system assuming that the mass of the disks is much greater than that of the shaft. Solve this problem in two ways:

(a) using a constraint matrix, and

(b) directly without a constraint matrix.