A metal rod of length L and mass m is pivoted at one end. A thin disk of mass M and radius R ( < L) is attached at its centre to the free end of the rod. Consider two ways the disc is attached : (case A). The disc is not free to rotate about its centre and (case B) the disc is free to rotate about its centre. The rod-disc system performs SHM in vertical plane after being released from the same displaced position. Which of the following statement(s) is(are) true?
Restoring torque in case A = Restoring torque in case B.
Restoring torque in case A < Restoring torque in case B.
Angular frequency for case A > Angular frequency for case B.
Angular frequency for case A < Angular frequency for case B.
Restoring torque = Force of gravity on disc and rod which is same in both cases.