centre of mass

[prat]

a rod is vertically placed in x-y plane
a slight disturbance is given to it so that it is inclined at an angle (90-a) with the horizontal.
find the acceleration of the centre of mass

i think that the path followed by the centre of mass would be elliptical so its acceleration can be gsina

[Mindscrape]

You need to find the inertia about the center of mass with respect to the axis that the rod is falling through.

[prat]

can you be more descripitive or suggest any way to solve the problem not understanding a bit

[Mindscrape]

Um, I personally feel like what I told you has been pretty descriptive. If you want more specifics then give more specifics to work with. I don't know what what's holding you up, I can't read minds. Say the rod rotates about x-axis, so find moment of inertia about the say x-axis (or the end of the rod), use conservation of energy for the center of mass, or torque, or lagrangian.