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Homework Help: Find diameter of steel wire - stress

  1. Mar 27, 2005 #1
    a) what is the diameter of a steel wire 18m long that elongates 9mm when a load of 380kg is hung on its end?
    b) if the elastic limit is 3.00E8 N/m^2, does permanent deformtion occur?

    a.
    [tex]\Delta L=FL/YA[/tex]
    [tex]9E-3m=\frac{3724N*18m}{20E10N/m^2*A}[/tex]
    [tex]A=3.724E-5m^2[/tex]
    [tex]diameter=6.8859mm[/tex]

    b.
    [tex]stress=F/A[/tex]
    [tex]stress=\frac{3724N}{3.724E-5m^2}[/tex]
    [tex]stress=1.00x10^8N/m^2[/tex]
    no deformation

    is that all correct?
     
  2. jcsd
  3. Mar 27, 2005 #2

    HallsofIvy

    User Avatar
    Science Advisor

    Looks good to me!
     
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