An equilateral triangle ABC formed from a uniform wire has two small identical beds initially located at A. The triangle is set rotating about the vertical axis A O. Then the beads are released from rest simultaneously and allowed to slide down one along AB and other along AC as shown. Neglecting frictional effects, the quantities that are conserved as the beads slide down, are :

Options

A. angular velocity and total energy (kinetic and potential)
B. total angular momentum and total energy
C. angular velocity and moment of inertia about the axis of rotation
D. total angular momentum and the moment of inertia about the axis of rotation

Answer

B

Explanation

Since no external torque acts on the whole system, the angular momentum remains conserved. As the beads slide the M.I. of the system changes. Now `L=Iomega` = constant, the angular velocity changes.
Also as the force acting on the system is conservative in nature the total energy of the system remains constant.