1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Length of wire with given yielding strength

  1. Jan 20, 2010 #1
    1. The problem statement, all variables and given/known data
    A steel wire is being hung from a high altitude balloon. What is the greatest length is can have without yielding if the steel yields at 40 ksi??


    2. Relevant equations
    I know all the stress and strain equations but I have yet to find or be taught an equation for finding this. I feel like it's very simple but I just can't figure is out. Stress= force/area
    Stress= (E-modulus)(strain)

    3. The attempt at a solution
    The answer is 11,800 ft or m, not sure which one. But I have no clue how to get to the answer. I did my homework and everything but this problem was "recommended" and I NEED to figure it out
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jan 20, 2010 #2

    nvn

    User Avatar
    Science Advisor
    Homework Helper

    megr_ftw: Hint: Wouldn't you want to compute the volume of the wire, and then the weight of the wire? Wouldn't the wire be carrying that weight?
     
  4. Jan 20, 2010 #3
    they dont give you the diameter so you cant calculate the volume
     
  5. Jan 20, 2010 #4

    nvn

    User Avatar
    Science Advisor
    Homework Helper

    Could you let the diameter be d?
     
  6. Jan 20, 2010 #5
    oh yea i guess that would be the easiest option. as long as it cancels in the end.

    The force of the wire's weight equals the buoyancy force created by the balloon right?
     
  7. Jan 21, 2010 #6

    nvn

    User Avatar
    Science Advisor
    Homework Helper

    Yes, you could say that. Well said.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook