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Homework Help: Elevator and weight question

  1. Sep 20, 2009 #1
    1. The problem statement, all variables and given/known data
    this should be simple question, but i could not get the answer. hope someone could point out my mistake.

    A person stands on a scale in an elevator. As the elevator starts, the scale has a constant reading of 587 N. Later, as the elevator later stops, the scale reading is 397 N. Assume the magnitude of the acceleration is the same during starting and stopping.

    3. The attempt at a solution
    Determine the weight of the person
    it should be 397N, since the scale shows 397N when the elevator stops. but my answer is wrong. why?
  2. jcsd
  3. Sep 20, 2009 #2

    D H

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    Staff Emeritus
    Science Advisor

    The elevator is stopping, not stopped, when the scale reads 397 N.
  4. Sep 20, 2009 #3

    Doc Al

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    Staff: Mentor

    As written, the question is poorly stated. They mean: While the elevator is speeding up, the scale reads 587 N; while it's slowing down, the scale reads 397 N.

    Once it stops, of course, the reading will equal his normal weight.
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