A potter has a stone disk of radius 0.483 m and mass 101 kg rotating at 71.9 rev/min. The potter stops the wheel in 6.54 seconds by applying a wet towel against the rim with a radially inward force of 103 N. Find the effective coefficient of kinetic friction between the whell and the wet towel.(adsbygoogle = window.adsbygoogle || []).push({});

my work

angular velocity= 71.9 x 2 x pi /60seconds=7.53

alpha =7.53 / 6.54=1.15

Torque=alpha x I = 1.15 x (101) x (.483^2) =27.13 N-M

27.13 = torque = F r sin 90

F =27.13/ (0.483)

F =56.17 Newtons = Frictional force

56.2 = u Fn

u=56.2 / (103) ----> 103 is given as the radially inward force, Fn

u=.545

why is this wrong? does anyone know why? thanks

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Torque problem involving rolling disk stopped by a force

**Physics Forums | Science Articles, Homework Help, Discussion**