1. The problem statement, all variables and given/known data A potter’s wheel—a thick stone disk of radius 0.500 m and mass 100 kg—is freely rotating at 50.0 rev/min. The potter can stop the wheel in 6.00 s by pressing a wet rag against the rim and exerting a radially inward force of 70.0 N. Find the effective coefficient of kinetic friction between wheel and rag 2. Relevant equations 3. The attempt at a solution Actually, I could get the answer using angular acceleration and torque, but I could do the same thing with Newtonian Laws and I want to know why. Tangential velocity of the wheel: 50 rev/ min = 2.618 m/s u = 2.618 m/s, v = 0, a = ?, t = 6 v = u + at 0 = 2.618 + 6a a = 0.436 m/s^2 Deceleration force F = ma = (100)(0.436) = 43.6N The friction coefficient 43.6 = (coefficient)(70) coefficient = 0.623, which is exactly the double of the correct answer. Thanks!