A coin placed 30.0 cm from the center of a rotating, horizontal turntable slips when its

a coin placed 30.0 cm from the center of a rotating, horizontal turntable slips when its speed is 50.0 cm/s. (a) what force causes the centripetal acceleration when the coin is stationary relative to the turntable? (b) what is the coeffi- cient of static friction between coin and turntable?