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Homework Help: Equation for solving the coefficient of Kinetic friction HELP?

  1. Feb 13, 2009 #1
    Equation for solving the coefficient of Kinetic friction HELP!?!?

    Problem: A cable attached to a block of mass 9 kg pulls the block along a horizontal floor at a constant velocity. If the tension in the cable is 5.2 N, what is the coefficient of kinetic friction between the block and the floor?




    Questions:I have tried to solve this but i really don't know where to begin.
    Whats the equation to calculate the coefficient of Kinetic Friction???


    Attempt: ok i know Mass= Friction/Gravity and gravity is 9.8,
    u=friction(k)/Normal force


    Fg= 9kg* (9.8)= 88.2 kg

    Ef=Ma = 5.2n +Ffk= 9kg * o m/s^2 = Ffk=-5.2 n

    [uk]= 5.2/100 = 0.052 m/s^2

    is this right??? so confused


    i really just don't have any idea about the the equation...HELP??
     
    Last edited: Feb 13, 2009
  2. jcsd
  3. Feb 13, 2009 #2

    Kurdt

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    Re: Equation for solving the coefficient of Kinetic friction HELP!?!?

    If the block is moving at a constant speed then there must be no net force on the block. That is the friction cancels out the force pulling it. Take a look at the following page about friction and have another go.

    http://hyperphysics.phy-astr.gsu.edu/hbase/frict2.html
     
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