Question

A hollow rod of mass, M is kept on a table. The rod is rotating with angular velocity ω when both rings of mass 'm' are situated on axis. Find angular Velocity of rings when they leave the rod.

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

As there is no net External torque on the system about its Axis {rod + rings}, the angular momentum of it should not change as time passes.

$\therefore L_i=L_f$

$\Rightarrow \frac{M{L}^2}{12}\times \omega =\{\frac{M{L}^2}{12}+\frac{M{L}^2}{4}+\frac{M{L}^2}{4}\}{\omega }_1\Rightarrow {\omega }_1=\frac{m\omega }{(M+6m)}$