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Homework Help: My calculations - youngs modulus

  1. Jan 31, 2012 #1
    Im about to hand coursework in. Its the youngs modulus of copper wire

    We added 100g weights and measured the extension using a traveling microscope.

    for example at 0.900kg the wire extended by 6.36cm

    my calculations are

    Diameter = d 2.7x10-5 m
    Cross section area A = Pi x d (squared) /4 = 5.7 x 10-8
    Applied Force F = (mxg) 0.900 x 9.81 = 8.82 kg m s-1
    Extension e = 0.0636 m
    Original length L = 1.788 m

    So Stress = F/A = 1.54 x 10(8)
    Strain = E/L = 3.6 x 10-2

    Stress / Strain = Youngs modulus E = 42 x 10(8) Pa

    Does this look correct?

    If i was to work out my mass / extension from my graph i would get this ...

    m/e = 14.2 x (gxL) 17.5 / A 5.73 x 10-8 = 4.3 x 10(9) pa
     
    Last edited: Feb 1, 2012
  2. jcsd
  3. Jan 31, 2012 #2
    Hi jokiemay,
    I found it hard to understand what you're doing because you never really explained anything, you just have us a bunch of values. i.e. the cross-sectional area of what? What is 6.36cm? Is 0.9kg the mass of said object?

    Help us to help you.
     
  4. Feb 1, 2012 #3
    ive edited the post above . thanks
     
  5. Feb 1, 2012 #4
    can anybody shine light on this ?
     
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