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NEET 2007 (AIPMT) · Rotational Kinematics & Dynamics

Rotational Kinematics & Dynamics question from NEET 2007 (AIPMT)

Q78NEET 2007 · AIPMTMedium

Rotational Kinematics & Dynamics

A uniform rod AB of length ll and mass m is free to rotate about point A. The rod is released from rest in the horizontal position. Given that the moment of inertia of the rod about A is ml2/3, the initial angular acceleration of the rod will be

Figure

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Answer: (c)

  1. Weight acts at the centre, l2\frac{l}{2} from A: τ=mgl2\tau = mg\frac{l}{2}.
  2. α=τI=mgl/2ml2/3=3g2l\alpha = \frac{\tau}{I} = \frac{mgl/2}{ml^2/3} = \frac{3g}{2l}
  3. So the answer is (c) 3g2l\frac{3g}{2l}.
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