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Homework Help: Reaction and friction coefficient on a cylinder

  1. Jan 28, 2015 #1
    1. The problem statement, all variables and given/known data
    The cylinder weighs 200[N] and lies on a rough surface. a rope holds it in place.
    What's the tension T in the rope and what's the minimal coefficient of friction.

    2. Relevant equations
    Friction: f=μN

    3. The attempt at a solution
    All the geometry i have drawn. T balances the torque made by the weight of the cylinder. i calculate torque round the point of contact with the inclined surface:
    The distance d from the line of action of T:
    $$d=\frac{R}{\tan30^0}\cdot \sin 60^0$$
    Now the torque from the weight equals the torque from T:
    $$200R\cdot \sin 30^0=T\cdot d\rightarrow T=66.7$$
    It should be 654 and i don't continue yet to the friction coefficient.
    Edit: i found my mistake, in newtons it comes out right. now i will try to find the coefficient of friction

    Attached Files:

    Last edited: Jan 28, 2015
  2. jcsd
  3. Jan 28, 2015 #2


    User Avatar
    2017 Award

    Staff: Mentor

    I get 654 N if the cylinder has a mass of 200 kg instead of a weight of 200N.

    654/66.7=9.81 made the difference clear.
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