A rod PQ of mass M and length L is hinged at end P. The

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A rod PQ of mass M and length L is hinged at end P. The rod is kept horizontal by a massless string tied to point Q as shown in figure. When string is cut, the initial angular acceleration of the rod is

1. g/L
2. 2g/L
3. 2g
  3L
4. 3g
  2L

Correct Option: D

Weight of the rod will produce the torque

τ = mg	L	= Iα =	mL²	α		∵ Irod =	mL²
	2		3				3

Hence, angular acceleration α = 3g/2L