One of the strings at end Q is cut at t = 0 and the rod starts rotating about the other end P. Then

At t = 0, acceleration of C.M. of rod is $\frac{3\mathrm{g}}{4}$ in downward direction.

At t = 0, tension in the string at P is $\frac{\mathrm{Mg}}{4}$

At t = 0, angular acceleration of rod about P is $\frac{3\mathrm{g}}{2\mathrm{L}}.$

At t = 0, angular acceleration of rod about C.M. of rod is $\frac{3\mathrm{g}}{2\mathrm{L}}$.