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Question 30353
JEE Physics · Hard

Rigid Body Dynamics: Angular Momentum — Disk Catch MCQ

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Angular Momentum — Disk CatchHardQuestion 30353

Question

A 2 kg disc (R = 0.5 m) spins at 10 rad/s. A 0.5 kg lump of clay (at rest) falls and sticks to the rim. New angular speed is:
  1. A
    10 rad/s
  2. B
    6 rad/s
    Correct
  3. C
    8 rad/s
  4. D
    5 rad/s

Correct answer

6 rad/s

Explanation

L = Iω. I₁ = ½×2×0.25 = 0.25 kg·m². L₁ = 0.25×10 = 2.5 kg·m²/s. I₂ = 0.25 + 0.5×0.25 = 0.25+0.125 = 0.375 kg·m². ω₂ = 2.5/0.375 = 6.67 ≈ 6 rad/s (nearest given).

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