5.11 A uniform circular disk of mass m and radius r rolls without slip along a plane inclined at a constant angle ß with horizontal as shown in Fig. P5-11. Attached at the center of the disk is a linear spring with spring constant K. Knowing that the spring is unstretched when the angle 0 is zero and that gravity acts downward, determine the differential equation of motion for the disk in terms of the angle 0.

5.11 A uniform circular disk of mass m and radius r rolls without slip along a plane inclined at a constant angle ß with horizontal as shown in Fig. P5-11. Attached at the center of the disk is a linear spring with spring constant K. Knowing that the spring is unstretched when the angle 0 is zero and that gravity acts downward, determine the differential equation of motion for the disk in terms of the angle 0.