The coefficient of friction between a certain brass block and a large revolving turntable is µ = 0.23. How far from the axis of rotation can the block be placed before it slides off the turntable if it is rotating at 33 1/3 rev/min? --- the only force on the block is the friction in the same direction as the centripetal acceleration, right? so... f = m * a(centripetal) 0.23 * N = m * v^2 / r = mRω^2, where ω = 2*pi*F(frequency), F = 1/(33 1/3) = 0.03 and N = mg. so, simplifying, 0.23*m*g = 100/3*m*R*ω^2, 0.23*g = 100/3*R*w^2 0.0069*g = R(w^2) R = 0.06762 / w^2, where w^2 = 0.03553 R = 1.9032 meters, which, apparently, is wrong. but why? my work seems right, and the answer sounds right... what have i done wrong?