Question
A thin circular ring of mass M and radius r is rotating about its axis with constant angular velocity ω. Two objects each of mass m are attached gently to the opposite ends of a diameter of the ring. The ring now rotates with angular velocity given by
-
(M +2m)ω /2m
-
2Mω / M + 2m
-
(M +2m)ω / M
-
Mω / M + 2m
Solution
D.
Mω / M + 2m
In the absence of external torque, angular momentum remain constant
L = Iω = I'ω'
therefore,
MR2ω = (M + 2m) R2ω'
ω' = Mω / (M + 2m)
