Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202118 MarchMorning Shift
Exam
JEE Main
Year
2021
Date
18 March
Shift
Morning Shift
Subject
Physics
Chapter
Rotational Motion

JEE Main 2021 · 18 March · Morning Shift · Physics · Rotational Motion

A thin circular ring of mass M and radius r is rotating about its...

A thin circular ring of mass MM and radius rr is rotating about its axis with an angular speed ω.\omega . Two particles having mass mm each are now attached at diametrically opposite points. The angular speed of the ring will become:

Options

  1. AωMM+m\omega\dfrac{M}{M + m}
  2. BωM+2mM\omega\dfrac{M + 2m}{M}
  3. CωMM+2m\omega\dfrac{M}{M + 2m}
  4. DωM−2mM+2m\omega\dfrac{M - 2m}{M + 2m}

Correct answer

C. ωMM+2m\omega\dfrac{M}{M + 2m}

Step-by-step solution

Using conservation of angular momentum
⇒(Mr2)ω=(Mr2+2mr2)ω′⇒ \left(M{r}^{2}\right)\omega = \left(M{r}^{2} + 2m{r}^{2}\right){\omega}^{'}

⇒ω′=MωM+2m⇒ {\omega}^{'} = \dfrac{M\omega}{M + 2m}.

Practice Rotational Motion on Quantrex Academy →

More from Rotational Motion

Consider a large disk of radius R and two smaller disks, each of radius r = R/50 , lying… JEE Advanced 2026A solid cylinder of radius R rolls without slipping with a center of mass speed v_0 =… JEE Advanced 2026List-I shows four planar structures made of uniform solid rods each of mass m and length… JEE Advanced 2026Passage: A uniform circular disk of radius 0.2 m and mass 1 kg is pivoted at its top… JEE Advanced 2026Passage: A uniform circular disk of radius 0.2 m and mass 1 kg is pivoted at its top… JEE Advanced 2026A solid cylinder having radius R and length L is slipping on a rough horizontal plane. At… JEE Main 2026A solid sphere ( A ) of mass 5m and a spherical shell ( B ) of mass m , both having same… JEE Main 2026A solid sphere of radius 4 cm and mass 5 kg is rotating (rotation axis is passing through… JEE Main 2026 Full Rotational Motion list All JEE Main PYQs