Determine the Maximum angular velocity

• chart2006

Homework Statement

The 10-lb slender rod AB is welded to the 6-lb uniform disk, which rotates about a pivot at A. A spring of constant k = 4.5lb/ft is attached to the disk and is unstretched when rod AB is horizontal. The assembly is released from rest in the position shown. Calculate and plot the angular velocity of the assembly after it has rotated through an angle θ, for values of θ from 0 to θm, the angle of maximum rotation. Determine the maximum angular velocity of the assembly and the corresponding values of θ.

Any help as to how to go about solving this would be greatly appreciated. I don't need it solved for me but info on how to set up the problem again would be appreciated. Thanks!

The Attempt at a Solution

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I'd start with a free-body diagram, but instead of forces, display torques about the fixed point at the center of the disk. Then add up all the torques to find the total torque on the assembly, and plug into $$\tau = I \ddot\theta$$ to get a differential equation for the angle.