A rod PQ of mass M and length L is hinged at end P. The rod is kepts 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 [NEET 2013] |
A) \[\frac{3g}{2L}\]
B) \[\frac{g}{L}\]
C) \[\frac{2g}{L}\]
D) \[\frac{2g}{3L}\]
Correct Answer: A
Solution :
Torque on the rod = Moment of weight of the rod about P |
\[\tau =mg\frac{L}{2}\] (i) |
\[\because \] Moment of inertia of rod about |
\[P=\frac{M{{L}^{2}}}{3}\] (ii) |
As \[\tau =la\] |
From Eqs. (i) and (ii), we get |
\[Mg\frac{L}{2}=\frac{M{{L}^{2}}}{3}\alpha \] |
\[\therefore \] \[\alpha =\frac{3g}{2L}\] |
You need to login to perform this action.
You will be redirected in
3 sec