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Simple coefficient of friction question

  1. Jun 3, 2010 #1
    Here's my givens... i need to find the coefficient of friction on the material.

    No load torque on motor - 3.19 Nm
    Loaded torque on motor - 3.49 Nm
    Surface area in contact with motor shaft - .1885"
    Mass of loaded material on shaft - 17.16 lbs = 76.33 N
    Rads/sec - 31.42

    Looking to find the coefficient of friction. I need formulas and assistance please, not answers :)

    Also, if I need to get/provide more information, I believe I can.

    Last edited: Jun 3, 2010
  2. jcsd
  3. Jun 3, 2010 #2
    alright, this came too easy. please confirm....

    torque = Radius x force

    which means rotational force = torque/radius

    loaded rotational force = 41.83/2" = 20.92 lbsf
    no load rotational force = 38.25/2" = 19.123 lbsf

    resistive force from load = 20.92 lbsf - 19.123 lbs f = 1.7928 lbs

    coefficient friction is (resistive force divided by rotational force) divided by 2

    CoF = (1.7928/20.92)/2 = 0.0428

    This seems realistic as this is plastic wearing against polished steel, in hot water. What do you guys think?
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