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Homework Help: Work question

  1. Feb 28, 2006 #1
    A plane weighing 220 kN (25 tons) lands on an aircraft carrier. The plane is moving horizontally at 63 m/s (141 mi/h) when its tailhook grabs hold of the arresting cables. The cables bring the plane to a stop in a distance of 89 m.

    (a) How much work is done on the plane by the arresting cables?

    (b) What is the force (assumed constant) exerted on the plane by the cables?

    This question is confusing me. I was under the impression that force needed to be calculated in order to find the work, but clearly they want me to find the work first. So, i went about trying to solve the problem:

    W= Force times distance

    The distance is equal to 89 meters. The force and the work, though, are both questions to be answered. Force = m times a....mass is 25000 kg, but acceleration isnt constant. Wherever I go with this problem i hit a dead end. Someone please help.
  2. jcsd
  3. Feb 28, 2006 #2

    Doc Al

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    Staff: Mentor

    While multiplying force by distance is the most direct way of calculating work, it won't help you here since you don't know the force. (As you realize.) In fact, part b asks you to find the force.

    But there are other ways to deduce the work done and thus the force of the cables. Hint: Consider the Work-Kinetic Energy theorem. (Look it up if you have to.)
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