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Homework Help: Force in an elevator during acceleration

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

    A woman stands on a scale in a moving elevator. Her mass is 60.0 kg, and the combined mass of the elevator and scale is an additional 815 kg. Starting from rest, the elevator accelerated upward. During the acceleration, the hoisting cable applies a force of 9410 N. What does the scale read during the acceleration?

    2. Relevant equations

    F= ma

    3. The attempt at a solution

    9410 = 9.8(815 + 60) * a

    I think the above equation is right, but not 100% on that. I can't figure out how to do the rest of this problem. Any help will be greatly appreciated. Thanks in advance!
  2. jcsd
  3. Nov 12, 2008 #2
    I believe you should solve the equation like this

    F = m*a

    since you are accelerating upwards a > 9.8m/s^2

    Using the given force and the given weight you can find the "new" acceleration.

    Using that acceleration you can find the force on the scale caused by the women.

    Then using that force you can determine what her weight will show, (since you can assume the scale reads weights based off a = 9.8m/s^2, so a larger force will result in a larger weight)

    Also, when you look at your above equation it is in the form F = m*a^2
    Last edited: Nov 12, 2008
  4. Nov 12, 2008 #3
    Awesome! Thanks for helping me out!
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