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Homework Help: Elevator homework problem

  1. Oct 17, 2004 #1
    Hello! This is my first time posting here! I'm so glad I found this site, it's helped alot already just by reading other people's questions! But now I have my own -
    A woman stands on a scale in a moving elevator. Her mass is 52.5 kg, and the combined mass of the elevator and scale is an additional 815 kg. Starting from rest, the elevator accelerates upward. During the acceleration, the hoisting cable applies a force of 9750 N. What does the scale read during the acceleration?

    I thought that I would find acceleration by using a=Fn/m and then putting acceleration into Fn=mg+ma.. but I can't seem to get the right answer.. help please?
  2. jcsd
  3. Oct 17, 2004 #2

    Doc Al

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    Staff: Mentor

    Welcome to PF!

    Those equations seem to contradict each other! :smile: Since I don't know what you mean by "Fn" (normal force? net force?), I can't tell which is correct.

    In any case, do this: First find the acceleration by considering the net force on the combined mass of "woman + elevator + scale" and applying Newton's 2nd law to that. Then apply Newton's 2nd law to the woman alone, making use of the acceleration you already found.
  4. Oct 17, 2004 #3

    thank you so much!!
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