A solid disk of mass M = 0.750 kg and radius R = 0.350 m is suspended vertically and is free to rotate about its center without friction. A point object that has the same mass as the disk is placed at an angle θi = 15.0° clockwise from the top along the rim, causing the disk to rotate. The acceleration due to gravity is g = 9.80 m/s^2. What is the angular speed ωf of the disk when the object is directly below the center of the disk?