Rotation 2 Question 10
10. An equilateral triangle $A B C$ formed from a uniform wire has two small identical beads 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 $A B$ and other along $A C$ 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 moment of inertia about the axis of rotation
(d) total angular momentum and moment of inertia about the axis of rotation
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Answer:
Correct Answer: 10. (b)
Solution:
- Net external torque on the system is zero. Therefore, angular momentum is conserved. Force acting on the system are only conservative. Therefore, total mechanical energy of the system is also conserved.
