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Homework Help: Youngs Modulus, help im lost

  1. Apr 11, 2008 #1
    1. The problem statement, all variables and given/known data

    Help I have spent a couple of days on this one and I am lost....

    What would the force constant be for a 75.0 cm length of 16-gauge (dia=1.291mm) copper wire? Y copper=11x10^10 Pa
    The answer being in Nm.
    The problem is I don’t even know where or how to approach this problem as when I have looked at hookes law and Young’s I fail to see how to fit this problem into the equations. I will accept lack of understanding, fatigue, or just plain stupidity on my behalf. If someone could spare the time to step me through it, i don't need this solved, just the steps so I can solve it myself. I would be grateful thanks

    2. Relevant equations

    3. The attempt at a solution
    Basically 8 pages of incomprehensible gibberish
  2. jcsd
  3. Apr 11, 2008 #2


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    Science Advisor
    Homework Helper

    I just answered that same question about steel. The units of Y are N/m^2. The force constant k is N/m. Let the cross sectional area be A and the length L. A REALLY good guess would be k=Y*A/L. Wouldn't it? Think dimensional analysis. Confirm it by looking it up or applying physical intuition.
  4. Apr 12, 2008 #3
    Sloved--- yeh

    Dick thanks for your help. The big issue I found is to change every thing into base units and work in scientific notation, a big part of my problem, how ever your gental push in the right direction has me now on track Big thanks
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