Finding the speed of the cylinder's point of mass

[Alif Yasa]

Homework Statement

In the picture

Relevant Equations

Force Equilibrium and Torque Equilibrium

I already got the answer for the case a
but at the case b, i don't know how to sum all of the torques.
I'm thinking of using integral, but i don't know where to put the pivot point for the torque.
I don't know how to search for the pivot point.
Can anybody give me hints so i could find the pivot point ?

 

[wrobel]

I'm thinking of using integral, but i don't know where to put the pivot point for the torque.

take cylinder's center of mass for a pivot point for example