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Physics Friction of a Sled

  1. Sep 30, 2009 #1
    1. The problem statement, all variables and given/known data

    A football coach sits on a sled while two of his players build their strength by dragging the sled across the field with ropes. The friction force on the sled is 1220 and the angle between the two ropes is 15.0. How hard must each player pull to drag the coach at a steady 1.80 ?


    2. Relevant equations

    Not sure on what equations to use.

    3. The attempt at a solution

    Haven't really attempted it cause I don't know how to start it. If someone could just give me the equations to use, I think I could get it.

    Thanks
     
  2. jcsd
  3. Sep 30, 2009 #2

    Delphi51

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    Homework Helper

    The pullers must match the force of friction. Their pulling force is partly wasted because they are not pulling straight ahead. You must sketch a vector at 15 degrees away from straight ahead, sketch in the rest of the right triangle of which the vector is the hypotenuse. Then use trigonometry to find the part of the F that is straight ahead. It will be F*cos(15) or F*sin(15). Finally, twice that will be equal to the friction force and you can then solve for F.
     
  4. Oct 1, 2009 #3

    Kurdt

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    Staff Emeritus
    Science Advisor
    Gold Member

    Please use units when posting quantities. They are meaningless without them.
     
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