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Homework Help: Young's Modulus Question

  1. Jan 31, 2017 #1
    1. The problem statement, all variables and given/known data
    A 10 kg load suspended by a brass wire 10 m long is observed to vibrate vertically in SHM at a frequency of 10 vib/s. Given that the Young's modulus for brass is gif.gif m%5E%7B2%7D.gif , what is the cross-sectional area of the wire?

    So we know:
    m = 10kg
    l = 10m
    f = 10Hz
    Y = 9x10^10
    2. Relevant equations

    Y = (F/A)/(delta l/l)

    3. The attempt at a solution
    We have solved Young's modulus problems but they have been very basic. Since this one includes what appears to be some sort of vertical movement/vibration, I don't know what to do because I don't know how the vib/s or Hz comes into play...
  2. jcsd
  3. Jan 31, 2017 #2


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    If you have studied SHM, then you know that a body moves in SHM when the body is subject to a force obeying Hooke's law. Did you learn how the vibrational frequency is related to the mass of the body and the force constant in Hooke's law?
  4. Jan 31, 2017 #3
    We did and I'm working on it and I think I'm on my way...

    At first I was so confused by the SHM because I had never seen it with any Young's mod problem but I am using Hooke's and Young's mod to find the actual stretch.

    I was able to isolate the k constant and I think maybe I can solve this
  5. Jan 31, 2017 #4


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    Sounds good.
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