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Relative extension

  1. Oct 19, 2010 #1
    1. Collagen fiber is stressed with 12 N force. The cross-sectional area of the fiber is 3 mm2, its coefficient of elasticity is 500 MPa. Give the percentage of relative extension.

    I think i have found the correct equation but i cant seem to find the rigth answer wich is suposed to be 0.8% but i always end up with 8*10^-4..

    2. Relevant equations

    F/A=E Δl/l

    3. The attempt at a solution

    12N/(0,003m^2 * 5*10^6 Pa)

    and then I get a result of 8*10^-4, and I am stuck.. I belive there is something fundamental I have missed but I can't seem to find it.. Thanks in advance!
  2. jcsd
  3. Oct 19, 2010 #2


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    welcome to pf!

    hi edorf! welcome to pf! :smile:

    (try using the X2 tag just above the Reply box :wink:)
    erm … 3 mm2 isn't .003 m2, is it? :redface:

    (and you left the 00 out of 500)
  4. Oct 19, 2010 #3
    ahhhhh...! Thank you so much!:D I guess thats what happends when you try to solve problems for 8h straight :P
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