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

(a)Angular velocity and total energy (kinetic and

potential)

(b)Total angular momentum and total energy

(c)Angular velocity and momentum of inertia about

the axis of rotation

(d)Total angular momentum and moment of inertia

about the axis of rotation

Ans: (b)

Sol: The net external torque on the system is zero .Therefore angular momentum is conserved .

The force acting on the system are only conservative , therefore total mechanical energy of the system is also conserved .