QJEEM21Phe5bc: JEE Main 2021 Physics - Class 11 JEEM21Phe5bc Solution: A thin circular ring of mass M and radius r is rotating about…

Question

Verified Solution • 2025–26 Session moderate

A thin circular ring of mass M and radius r is rotating about its axis with an angular speed

ω

. Two particles having mass m each are now attached at diametrically opposite points. The angular speed of the ring will become :

Accepted Answer

τ

_net = 0, so angular momentum is conserved

By angular momentum conservation

I_i

ω

_i = I_f

ω

_f

(MR²)

ω

= (MR² + 2mR²)

ω

_f

ω

_f =

\frac{(M R^{2}) ω}{M R^{2} + 2 m R^{2}} = \frac{M ω}{M + 2 m}

ω_{f} = \frac{M ω}{M + 2 m}

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