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!

Stretching of a Steel wire

  1. Mar 27, 2015 #1
    1. The problem statement, all variables and given/known data
    A steel wire 2.9mm in diameter stretches by 0.038{\rm \\%} when a mass is suspended from it. The elastic modulus for steel is 2.0×1011N/m2

    *that {\rm \\%} value is in my homework, I assumed it was a mistake and was meant to be mm
    2. Relevant equations
    young's module for elasticity F/A=E(Δl/l)

    3. The attempt at a solution
    So to answer this I think I need to find F because that equals mg, so I'll just divide F by 9.8.

    However I'm not given l so inserting the numbers into the equation I get
    F/ [(.5*.0029)^2*π]=2.0*10^11{[(l+.00038)-l]/l}
    There are two unknowns and I don't know about other equations to answer this problem, usually original length is given so I'm very confused.
     
  2. jcsd
  3. Mar 27, 2015 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    It's not clear what you are supposed to find here, F or the length of the wire.
     
  4. Mar 27, 2015 #3
    The exact question is "How large is the mass?"
     
  5. Mar 27, 2015 #4

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    What if instead of the wire stretching by 0.038 mm, it stretched by 0.038% of its original length?
     
  6. Mar 27, 2015 #5
    That makes so much more sense and I was able to solve it, thank you so much I was working on this problem forever :)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Stretching of a Steel wire
  1. Stretching a wire (Replies: 10)

Loading...