1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

    245N=(5e9)(?/30.2)(.0266)

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

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?