physics
posted by jaeny .
A coin of 5.30 gram is placed 12.0 cm from the center of a turntable. The coin has static and kinetic coefficients of friction with the turntable surface of = 0.900 and = 0.470.
What is the maximum angular velocity with which the turntable can spin without the coin sliding?

The static friction coefficient, Us, determines when it starts sliding.
M*g*Us = M*R*w^2
Solve for w, the angular velocity.
w = sqrt(g*Us/R) = 8.57 rad/s