Physics help please!?

1. A coin is placed 15.0 cm from the axis of a rotating turntable of variable speed. When the speed of the turntable is slowly increased, the coin remains fixed on the turntable until a rate of 30 rpm is reached, at which point the coin slides off. What is the coefficient of static friction between the coin and the turntable?














2.A jet pilot takes his aircraft in a vertical loop





(a) If the jet is moving at a speed of 1900 km/h at the lowest point of the loop, determine the minimum radius of the circle so that the centripetal acceleration at the lowest point does not exceed 6.0 g's.


____ m


(b) Calculate also the 72 kg pilot's effective weight (the force with which the seat pushes up on him) at the bottom of the circle.


____N


(c) Calculate the pilot's effective weight at the top of the circle. (Assume the same speed.)


____N

Physics help please!?
1. μmg = m ω^2 r


μ = ω^2 r / g


μ = (30*2π/60 rad/s)^2 (0.15 m) / (9.8 m/s^2)


μ = 0.151