Posted by Emily Gutenber on .
a 70 kg object sits without sliding on a horizontal platform that rotates at a constant rate of one revolution every 6 seconds about a fixed vertical axis. The object moves on a circle of radius r=2m. If meu is now .4 what is the max distance from the cetner that the object can occupy to rotate with out sliding?

Ap Physics 
drwls,
You don't need to know the mass or initial radius to answer your questio.
The angular velocity remains
w = 2 pi rad/6 s = 1.047 rad/s
I assume that waht you call meu is the coefficient of STATIC friction, which is what matters here. I will call it mu.
The maximum noslip radius R when rotating at angular velocity w is given by the relation:
Max. noslip friction force = centripetal force
M*g*mu = M*R*w^2
The mass M cancels out.
R = g*mu/w^2 = 3.58 m