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Homework Help: How much is it lengthened from its untensioned length of 30.2 cm?

  1. Nov 8, 2007 #1
    1. The problem statement, all variables and given/known data

    A nylon tennis string on a racket is under a tension of 245 N. If its diameter is 0.92 mm, by how much is it lengthened from its untensioned length of 30.2 cm?

    2. Relevant equations

    F=E(delta L/L initial)A

    3. The attempt at a solution


    delta L = 6.1e-8cm
  2. jcsd
  3. Nov 8, 2007 #2


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    You know the stress, to find the strain you need to know Young's modulus for Nylon.
    That is the ratio of the stress to the strain ( can't remember which way round )
  4. Nov 8, 2007 #3
    elastic modulus for nylon is 5e9
  5. Nov 8, 2007 #4
    that seems right. does that not match with the answer? Its been a while since i used that equation
  6. Nov 8, 2007 #5
    So you'll want to convert the diameter and the "untensioned length" to meters. Also, you want to think of the cross sectional area as the area of a circle, which you know the diameter of. Does that help?
  7. Nov 8, 2007 #6
    oh ya it has to be in meters. and mm is 1x 10^-3 meters.
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