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Homework Help: Need help quick with frictional force

  1. Oct 20, 2008 #1
    1. The problem statement, all variables and given/known data

    A force of 43.0 N accelerates a 5.0-kg block at 6.1 m/s2 along a horizontal surface.
    How large is the frictional force?

    What is the coefficient of friction?

    2. Relevant equations
    F = ukFn

    3. The attempt at a solution
    Fthrust = Ffriction = ukFn = ukFg = uk x m x g = ? x 5.0 kg x 6.1 m/s/s
    Last edited: Oct 20, 2008
  2. jcsd
  3. Oct 20, 2008 #2
    no one can help me?
  4. Oct 20, 2008 #3
    bump. i need help please
  5. Oct 20, 2008 #4
    What's the total force on the block?
  6. Oct 20, 2008 #5
    43 N i think. thats all the givens i have
  7. Oct 21, 2008 #6
    No, you clearly have more "givens." And 43 N is NOT the total force.
  8. Oct 21, 2008 #7
    here the net force of the system is ma

    take the forces, -------->u have the applied force...(43N) and the force against it which u dont have (Ff) and equate it to the net force

    so, ma = Fapplied - Ffriction

    i thinks thats how u solve it...i can be wrong...

    once you solve for friction force, you can easily solve for mu by with Ff = muFn
  9. Oct 21, 2008 #8
    Yes, that's how you solve it, but it gives a bit too much information. The poster has to do some work too!
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