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Homework Help: Lagrangian of suspended rod

  1. Nov 5, 2012 #1
    1. The problem statement, all variables and given/known data
    A thin rod of length 2b is suspended by 2 light strings both attached to the ceiling. Using x, y1, y2 as your generalized coordinates right down the lagrangian of the system. Where x is the longitudinal displacement of the rod and y1 and y2 are the horizontal displacements of the ends.

    2. Relevant equations

    The strings remain taught and displacements from equilibrium are small

    3. The attempt at a solution
    If θ Is the angle that one of the strings makes with the vertical and we make a small angle approximation then θ= (x^2 +y^2)/l but and the height above the equilibrium position is equal to l(1-cos θ) which is approximately equal to l(θ^2), but this gives me a bunch of very small terms which I don't think is correct
  2. jcsd
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