JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyApplication

JEE Main 18 March 2021, Shift 1, Physics Q20

Question 20 of 90 in this shift, Physics question 20 of 30, Section A.

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

\omega

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

(1) $\omega\frac{M}{M+m}$
(2) $\omega\frac{M}{M+2m}$ Official answer
(3) $\omega\frac{M-2m}{M+2m}$
(4) $\omega\frac{M+2m}{M}$

Official answer

Option 2

NTA final key.

Chapter: System of Particles and Rotational Motion
Topic: Angular Momentum
Idea tested: Conservation of Angular Momentum

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.