question_answer

A thin circular ring of mass m and radius R is rotating about its axis with a constant angular velocity\[\omega \]. Two objects each of mass M are attached gently to the opposite ends of a diameter of the ring. The ring now rotates with an angular velocity\[\omega '\]is equal to                                                                                  [AIEEE 2006]

A)   \[\frac{\omega (m+2M)}{m}\]  

B)        \[\frac{\omega (m-2M)}{(m-2M)}\]

C)   \[\frac{\omega m}{(m+M)}\]    

D)       \[\frac{\omega m}{(m+2M)}\]

Correct Answer: D

Solution :

[d] As external torque is acting about the axis, angular momentum of system remains conserved.