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Homework Help: Force question

  1. Feb 16, 2008 #1
    1. The problem statement, all variables and given/known data

    Jarek is motoring along when he spots Chris and Michelle thumbing a ride back to Winnipeg. He hitches them up to two ropes and accelerates westward towards Winnipeg, He pulls with a constant force on a rope which slopes down 30 degrees to Chris's belt. A second rope attached to Chris' belt pulls Michelle's belt. Assume there is no friction force between the level snow-covered road and their skis and that the only motion is their acceleration west. Calculate the tension in the rope joining Michelle and Chris. Mass of Chris = 70Kg; mass of Michelle = 50Kg; mass of Jarek = 60Kg; mass of motorcycle = 100Kg.

    2. Relevant equations

    Chris= 70Kg
    Michelle= 50Kg
    Jarek= 60Kg + 100Kg; 160Kg
    a= constant

    Fnet = mg

    3. The attempt at a solution

    Fnet = mg
    = (50Kg)(9.8N/Kg)
    = 490N

    Fnet = Ff + Fa
    Ff = 0
    Fa = 490N [W]

    It seems a little too simple, can someone please check over my work? Thanks, I really appreciate it.
  2. jcsd
  3. Feb 16, 2008 #2

    Doc Al

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    Staff: Mentor

    Are you given any information about the force exerted or the acceleration?
  4. Feb 17, 2008 #3
    Thanks for replying Al; that's what had me thinking...

    All the question says about force is that it's constant, it doesn't give any values for acceleration or force.
  5. Feb 17, 2008 #4

    Doc Al

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    Staff: Mentor

    Then I don't see how you can answer the question. (Double check that you copied the question exactly as given.)
  6. Feb 17, 2008 #5
    That's the exact question. My teacher said that it was possible though =(
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