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  1. A uniform rod AB of length , 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
    1. mgl
      2
    2. 2
      gl
      2
    3. 3g
      2l
    4. 2g
      3l
Correct Option: C


Weight of the rod will produce torque,
τ = mg × (i/2)
Also, τ = Iα
where, I is the moment of inertia = ml²/3
and α is the angular acceleration

ml²
α = mg ×
⇒ α =
3g
322l



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