What is the coefficient of static friction between the coin and the turntable?

Question

A coin is placed 25 cm from the center of a horizontal turntable, initially at rest. The turntable then begins to rotate. When the speed of the coin is 110 cm/s (rotating at a constant rate), the coin just begins to slip. The acceleration of gravity is 980 cm/s 2 . What is the coefficient of static friction between the coin and the turntable?

Answer 1

μmg = mv²/r; μ = v²/(rg) = 1.1²m²/s²/(0.25m/s·9.8m/s²) = 0.494