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Homework Help: Friction in an elevator

  1. Oct 6, 2008 #1
    1. The problem statement, all variables and given/known data
    You are riding in an elevator on the way to the eighteenth floor of your dormitory. The elevator's upward acceleration is a= 1.84 . Beside you is the box containing your new computer; box and contents have a total mass of 28.9 kg. While the elevator is accelerating upward, you push horizontally on the box to slide it at constant speed toward the elevator door.

    a)If the coefficient of kinetic friction between the box and elevator floor is uk= 0.31, what magnitude of force must you apply


    2. Relevant equations
    n=mgcosθ


    3. The attempt at a solution
    fy=n-mg=ma
    n=m(a+g)=336.396
    fk=un=0.31*336.396=104.28

    I think this is the solution but I'm not entirely sure. As always any help is appreciated.
     
  2. jcsd
  3. Oct 6, 2008 #2

    PhanthomJay

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    Gold Member

    Yes, looks good. But don't forget the proper units for the force.
     
  4. Oct 6, 2008 #3
    thanks for te vote of confidence, I was a little worried I was wrong but I'm right thankfully :)
     
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