Angular acceleration

Jul 2008
60
1
Hey guys.
I got this poll which is at one side connected to a wall and is being released from a horizontal state.
his length is L and mass m.
I need to find the angular acceleration of the poll as a function of the angle.
I got this answer in the pic but according to them the answer should be what I marked in the red box.

Any idea? am I wrong?

10x.
 

Attachments

Jul 2008
60
1
Ok, I know what the problem is, I made a mistake in the moment of inertia...(Blush)

I do have another question due.(Nod)
First of all, when they say this is the angular acceleration of the poll, does it mean the angular acceleration of the center of mass?
In the next part of the question, they ask for the angular velocity as a function of \(\displaystyle \varphi\).
I tried to use energy conservation and came up with this equation:
\(\displaystyle mgL=mgL(1-1/2\cos(\varphi))+1/2 mv^2+1/2 I\omega^2\)
When
\(\displaystyle v = \omega*(L/2)\)

Is this right?

10x.