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Homework Help: Elevator spring problem

  1. Dec 9, 2004 #1
    What will a spring scale read for teh weight of a 58 kg woman in an elevator that moves (a) with a constant upward speed of 6.0 m's, (b) with a constant downward speed of 6.0 m/s, (c) with upward acceleration of 0.33g, (d) with downward acceleration of 0.33g, and (e) in free fall?

    I'm having trouble with a and b. (c and d are easy enough because the g is given and e is weightless because it's free fall.) I don't know where to start!
  2. jcsd
  3. Dec 9, 2004 #2


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    Force equals mass times acceleration. The scale will read the weight of the woman (NOT mass)

    plus her mass times acceleration upward.

    minus her mass times acceleration downward.

    with no acceleration (just constant speed) the scale will read her weight.

    In free fall, mass times downward acceleration equals weight so there would be no reading.
  4. Dec 10, 2004 #3
    The balance provides all the tension to the man,R.
    That's to say, R-F=net force
  5. Dec 10, 2004 #4


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    But there was no man!
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