A soccer ball (radius R = 11 cm) is sitting at rest on the ground when it is kicked. For this problem, we can model the ball as a hollow sphere. The kicking force is directed hori- zontally and radially inward, so that the ball has zero initial spin. (Therefore, the ball is slipping on the ground immedi- ately after it is kicked) If the ball has an angular acceleration of a = 55 rad/s² immediately after it is kicked, then what is the coefficient of friction με between the ball and the ground?