Physics
posted by Alex .
A coin is placed on an old record turntable which rotates at 78 rpm. The coefficient of friction between the record and the coin is 0.17.
a) What is the angular speed of record in radians/s?
b) At what distance (m) from the center will the coin begin to slide off the record?
c) What is the period of the rotation (s) of the penny?

a) convert 78 rev/min to radians/sec. Call that number w.
b) R*w = 0.17 * M*g
Solve for radius, R.
c) Why would the penny rotate? It revolves about the turntable center before it starts slipping. It does not rotate while revolving.