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Homework Help: Stress & strain for steel wire

  1. Mar 31, 2013 #1
    A 1.80-m long round steel wire with a cross-sectional diameter of 0.80 mm is placed over a light frictionless pulley, with one end of the wire connected to a 23.0-kg mass and the other end connected to a 14.0-kg mass. By how much does the wire stretch when the masses are in motion?

    S= F/A
    e= ΔL/L°
    S= Ye (where Y is Young's modulus for steel= 210 GN/m^2)

    I figured the F i needed in the first equation would be the tension in the wire. I got 171N for that answer and then I applied it to S= F/A. I found my S to be about 340163 N/m^2. I don't know whether to use that S for S=Ye or not. Where do I go from here?
    Last edited: Mar 31, 2013
  2. jcsd
  3. Mar 31, 2013 #2


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    Staff Emeritus
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    Gold Member

    I haven't check your numbers, but yes, the tensile stress is the tension force divided by the cross-sectional area, and this is the stress that goes into your equation involving young's modulus.
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