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Youngs Modulas

  1. May 22, 2005 #1
    Youngs Modulus

    Hey guys, i tried this problem on youngs modulas and got the wrong answer :surprised

    So i was wondering if anyone could tell me where i went wrong here or tell me how to do it properly.


    A 20cm brass wire of radius 1.0mm
    experiences an elongation of 0.49mm
    when a tensile force of 1.0 kN is applied.
    Calculate the youngs modulas of brass.

    σ = F/A

    F=1000 N

    Є = 4.9*10^-4/1.0X10^-3
    σ = 1000/0.2*0.001
    E= (1000/0.2*0.001)/(4.9*10^-4/1.0X10^-3)
    That came out as 1.0*10^7 for me.
    The answer is apparently 1.3*10^11

    Any help on this would be good.
    Last edited: May 22, 2005
  2. jcsd
  3. May 22, 2005 #2


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    The cross sectional area is wrong...

  4. May 22, 2005 #3
    mmm, wires, 3.142r^2...
  5. May 22, 2005 #4


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    Yep,that's right.And the length L is wrong as well.

  6. May 22, 2005 #5
    calculation mistake rather than conceptual mistakes..
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