A thin, uniform stick of length 2.6 m and mass 4.1 kg is pinned through one end and is free to rotate. The stick is initially hanging vertically and at rest. You then rotate the stick so that you are holding it horizontally. You release the stick from that horizontal position. What is the magnitude of the angular acceleration of the stick when it has traveled 20.9 degrees (the stick makes an angle of 20.9 degrees with the horizontal)?
Remember that the moment of inertia for a stick of mass m and length L about its end is (1/3)mL2.