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Question 6171
NEET Physics · Hard

System of Particles & Rotational Motion: Rotational Dynamics MCQ

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Rotational DynamicsHardQuestion 6171

Question

A pulley (I=0.1 kg·m², R=0.2 m) has mass M=1 kg hung from a light string. Its angular acceleration (g=10 m/s²) is:
  1. A
    100/7 rad/s²
    Correct
  2. B
    10 rad/s²
  3. C
    20 rad/s²
  4. D
    8 rad/s²

Correct answer

100/7 rad/s²

Explanation

For the falling mass, Mg−T=MaMg-T=Ma; for the pulley, TR=IαTR=Iα and a=αRa=αR. Thus a=Mg/(M+I/R2)=10/(1+2.5)=20/7a=Mg/(M+I/R^2)=10/(1+2.5)=20/7 m/s², so α=a/R=<strong>100/7 rad/s2</strong>α=a/R=<strong>100/7\text{ rad/s}^2</strong>.

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