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Homework Help: Help with question on forces with motion, tension, friction

  1. Oct 1, 2008 #1
    1. The problem statement, all variables and given/known data
    http://img253.imageshack.us/my.php?image=workshownph1.jpg


    2. Relevant equations

    The equations and the problem, along with the attempt at a solution are shown in the picture above

    3. The attempt at a solution

    The attempt is in the picture as well. Thanks guys for looking at it and helping out in advance. I have no idea with these sorts of problems where to start or what im doing wrong.
     
  2. jcsd
  3. Oct 1, 2008 #2

    LowlyPion

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    Homework Helper

    Welcome to PF.
    What are you given for the coefficient of friction?
     
  4. Oct 1, 2008 #3
    Thanks, its good to be here. Unfortunately all i am given is what is shown in the picture. I just assumed there was friction since it didn't say there wasn't.... thats why its in my equations.
     
  5. Oct 1, 2008 #4

    LowlyPion

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    Homework Helper

    Your equations are inaccurate. The tension must allow for the weight of both box and sled as the sinθ from the incline.

    There should be a μ*m*g*cosθ between the box and the sled. When acceleration of the combined system exceeds that then it will slip. But not knowing that μ ... if it was frictionless on the sled it would slide with any tension on the rope.
     
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