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Homework Help: Length of Simple Elastic Rods in Equilibrium

  1. Feb 9, 2008 #1
    1. The problem statement, all variables and given/known data

    I have a simple structure made up of joints and rods. Please feel free to check out the diagram here:

    http://rsizr.com/etc/hardelastics.pdf" [Broken]

    The rigid rods do not deform, and the elastic rods will deform only in the horizontal dimension. If all five elastic rods are the same material, same rest length (length = 1) and only respond to axial forces at the endpoints, what will be their equilibrium lengths given the structure?

    Please ignore gravity, friction, or anything else unmentioned. Thanks very much for your help!

    2. The attempt at a solution

    I came up with a solution to an easier version of this problem:

    http://rsizr.com/etc/elasticsprob.pdf" [Broken]

    Through simple introspection, using these equations:

    x+y = 5
    y+z = 3

    solution: x = 7/3, y = 8/3, z = 1/3

    This solution seems to make sense but I am also not sure because it's not grounded with real physics equations :)

    (I tried to apply equations for elastic equilibrium but got lost...)
    Last edited by a moderator: May 3, 2017
  2. jcsd
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