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Homework Help: Object being pushed up an inclined plane

  1. Dec 14, 2005 #1
    I can't figure out how to get the mass of this object, with the information given:

    Inclined plane with angle relative to the ground of 20 degrees.

    It takes 70 Newtons to get the object moving up the plane.

    "Mu" of static friction: 0.35

    All my example problems involve an object going down an inclined plane. I have been working on this problem all day, and just seem to get myself more and more confused. Any help would be appreciated.
  2. jcsd
  3. Dec 14, 2005 #2
    try drawing a free body diagram- the forces acting on the block are the push, friction, the normal force, and weight.
  4. Dec 14, 2005 #3
    I have :(. I don't know the weight, only what I gave above. It seems to me like I need one more piece of information, such as the weight. That is why I posted here, to see if I was missing something obvious.
    Last edited: Dec 14, 2005
  5. Dec 14, 2005 #4
    well, you are solving for the weight, to get the mass.

    you know that [itex] F_f = \mu N = \mu Wcos(\Theta) [/itex]
  6. Dec 14, 2005 #5
    So that means:

    Fsubf = 24.5

    24.5 = mu x W x cosTheta

    24.5/(mu x cosTheta) = W

    Thank you so much, I did not recall that relationship between the Friction force and muN.
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