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Homework Help: Youngs modulus

  1. Nov 5, 2006 #1
    A wire of length 4.95 m with a cross-sectional area of 0.103 cm^2 stretches by 6.55 mm when a load of 0.94 kN is hung from it. What is the Young's modulus for this wire?

    FA = Y (delta L/L)

    0.103 (cm^2) = 1.03 × 10-5 m^2
    6.55 millimeters = 0.00655 meters

    = 9221.4 N x 1.03 × 10-5 m^2 = .09498

    0.00655m / 4.95m = 0.00132323232
    .09498 / 0.00132323232 = 71.7787788 Pa ????

    what did i do wrong?
     
  2. jcsd
  3. Nov 5, 2006 #2

    radou

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    [tex]\Delta l = \frac{Fl}{YA} \Rightarrow Y = \frac{Fl}{\Delta l A}[/tex].
     
  4. Nov 5, 2006 #3
    Y = 940N * 4.95m
    ------------
    .00655m * 1.03(10^-5)m^2

    Y = 6.90356083 × 10^10

    Does this seem correct? thanks for the help
     
  5. Nov 5, 2006 #4

    radou

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    Yes, it seems correct.
     
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