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Homework Help: Maximum Tension

  1. Feb 12, 2008 #1
    1. The problem statement, all variables and given/known data

    A horizontal rope pulls a 10kg wood sled across frictionless snow. A 5.0kg wood box rides on the sled. The coefficient of static friction for wood on wood is mu = 0.5.

    What is the largest tension force for which the box doesn't slip?

    2. Relevant equations

    f(static) = mu * f(normal)

    3. The attempt at a solution

    I dont really see how the mass of the sled is relevant. But heres what I did:

    f(static) = 0.5 * 5(9.81) = 24.5N
  2. jcsd
  3. Feb 12, 2008 #2
    You've calculated the maximum horizontal force the sled can exert on the 5 Kg box. That is not the whole answer to the question though.

    In order to exert that force and accelerate the box, the sled itself must also be accelerating, and therefore you must calculate the acceleration that the 5 Kg box would undergo with a force of 24.5 N acting on it. The max tension in the rope would be the force required to accelerate the box AND the sled.
  4. Feb 12, 2008 #3
    ah ok. Thanks for the reply.
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