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Homework Help: Compression problem

  1. Nov 10, 2006 #1
    A 57-kg water skier is being pulled by a nylon (Young's modulus 3.7 x 109 N/m2) tow rope that is attached to a boat. The unstretched length of the rope is 18 m and its cross-section area is 1.9 x 10-5 m2. As the skier moves, a resistive force (due to the water) of magnitude 190 N acts on her; this force is directed opposite to her motion. What is the change in length of the rope when the skier has an acceleration whose magnitude is 0.81 m/s2?

    Ok here is what I was able to do so far I know that

    F = Y(Delta L/L0)A

    When I solve for Delta L I know that Delat L = FL0/ Y(A).

    I just don't know how to factor in the acceleration and most importantly how to use the 190 N resistence force?

    Please let me know and thanks a lot.

  2. jcsd
  3. Nov 10, 2006 #2


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    The acceleration of the skier is the result of the net force acting. The net force is the combination of the force from the rope and the resistive force.
  4. Nov 10, 2006 #3
    oh ic ic.

    That explains it so much better.

    Thank you so much.
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