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Lagrange's equations

  1. Jan 16, 2016 #1
    Lagrange's equation of the first kind gives us ∂L/∂q-(d/dt)(∂L/∂q.)=Q and the Euler-Lagrange equations give us ∂L/∂q-(d/dt)(∂L/∂q.)=0 (I know the equations are not perfectly written but you get the point). How do you know which one to use?
  2. jcsd
  3. Jan 16, 2016 #2
    The second one only account for conservative forces. When you have forces that ain't conservative the right side is the sum of these forces.
    (Assuming I understood your notation correctly, been a long time since I did this)

    Edit: maybe someone else can give their input, after checking it again I suspect I may have give you a (way) too simplistic answer.
    Last edited: Jan 16, 2016
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