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Homework Help: Potters wheel coefficient of kinetic friction

  1. Mar 25, 2012 #1
    1. The problem statement, all variables and given/known data

    A potter's wheel having a radius 0.49 m and a moment of inertia of 10.6 kg · m2 is rotating freely at 52 rev/min. The potter can stop the wheel in 5.5 s by pressing a wet rag against the rim and exerting a radially inward force of 68 N. Find the effective coefficient of kinetic friction between the wheel and the wet rag.

    2. Relevant equations

    I = .5mr^2

    3. The attempt at a solution

    I wasnt sure where to start. I know how to solve for the mass of the wheel, I know the moment of inertia formula and I know that the coefficient of kinetic friction is equal to μN. I drew a picture of the situation but am not sure how the moment of inertia and the decelleration are going to relate to the force that is applied.
  2. jcsd
  3. Mar 25, 2012 #2


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    Homework Helper

    welcome to pf!

    hi arogers5! welcome to pf! :smile:

    first do the geometry, then the physics

    the geometry is the angular acceleration: find it from the given initial and final speeds, and the time

    then use the moment of inertia to find the total torque

    then subtract to find the friction :wink:
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