A thin circular ring of mass M |RIGIDBODYDYNAMICSJEEMain2022

JEE MAIN 2022

26-06-2022 S1

Question

A thin circular ring of mass M and radius R is rotating with a constant angular velocity 2 $\mathrm{rads}^{-1}$ in a horizontal plane about an axis vertical to its plane and passing through the center of the ring. If two objects each of mass m be attached gently to the opposite ends of a diameter of ring, the ring will then rotate with an angular velocity (in rads-1).

Select the correct option:

$\frac{\mathrm{M}}{(\mathrm{M}+\mathrm{m})}$

$\frac{(\mathrm{M}+2 \mathrm{~m})}{2 \mathrm{M}}$

$\frac{2 \mathrm{M}}{(\mathrm{M}+2 \mathrm{~m})}$

$\frac{2(\mathrm{M}+2 \mathrm{~m})}{\mathrm{M}}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution

Applying conservation of angular momentum $$ \begin{aligned} & M R^2 \omega=\left(M R^2+2 m R^2\right) \omega^{\prime} \\ & \omega^{\prime}=\frac{2 M}{M+2 m} \end{aligned} $$

Question Tags

JEE Main

Physics

Easy

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