JEE Main202118 Mar 2021Morning ShiftPhysicsRotational MotionActual
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:
Options
- Aω M M + m
- Bω M + 2   m M
- Cω M M + 2   m
- Dω M - 2   m M + 2   m
Correct answer
C. ω M M + 2   m
Step-by-step solution
Using conservation of angular momentum ⇒ M r 2 ω = M r 2 + 2 m r 2 ω ' ⇒ ω ' = M ω M + 2   m .