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A 4.4kg block is pushed along the ceiling

  1. Oct 14, 2012 #1
    1. The problem statement, all variables and given/known data

    A 4.40 kg block is pushed along the ceiling with an constant applied force of F = 84.0 N that acts at an angle θ = 50° with the horizontal. The block accelerates to the right at 6.92 m/s2. Determine the coefficient of kinetic friction between the block and the ceiling.


    2. Relevant equations
    u_k=(F_k)/(F_n)
    ƩF=m*a
    (pythagorean theorem for F_n)


    3. The attempt at a solution
    I've tried this problem multiple different ways, but I keep getting a number that is greater than 1. Thank you!

    F_n=(4.4*9.8)-(84*sin50)=-21.227733
    -F_k=(4.4*6.92)-(84*cos50)=-23.546259
    u_k=1.1092
    but 0<u_k<1
     
  2. jcsd
  3. Oct 15, 2012 #2

    CWatters

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    Science Advisor
    Homework Helper

    I haven't checked your working but..

    http://en.wikipedia.org/wiki/Friction#Coefficient_of_friction

     
  4. Oct 17, 2012 #3
    Thank you!! That cleared up some of the confusion!!
     
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