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Physics prob 2 Help needed

  1. Oct 12, 2008 #1
    Physics prob 2 ... Help needed!!!

    1. The problem statement, all variables and given/known data

    Like i sayed in my other posts this is probably easy but my teacher doesn't teach us anything so i don't have a clue how to do this. Can someone please explain how to do it?

    A window washer pushes a sponge up a vertical window at a constant speed by applying a force. The sponge has a mass of .800 kg, and the coefficient of kinetic friction between the sponge and window is u_k=0.253. Determine the magnitude of the applied force, and the magnitude of the normal force exerted by the window on the sponge.

    *There is a 20 degree angle( i put the pic below)

    2. Relevant equations

    F(y) = weight of sponge + Frictional force

    F(f) = u*F(x)

    3. The attempt at a solution

    ok so what i did was that i took the sin 70 which if i'm not mistaken should equal F(x).
    sin 70=F(x)

    Then I put this in the equation for frictional force.

    After that I put it in to the equation for F(y).
    F(y)=weight of sponge + F(f)

    My plan is to do the pythagorian therum to find the applied force, but I want to make sure i am doing it right so far.

    Attached Files:

    • p.bmp
      File size:
      292.6 KB
  2. jcsd
  3. Oct 13, 2008 #2


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    Re: Physics prob 2 ... Help needed!!!

    F(x) = F * sin(70)

    where F is magnitude of the applied force.
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