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Independent variables of the Lagrangian

  1. May 6, 2014 #1
    Why are y and y' treated as independent variables, while they are not?

    Another slightly related question:
    if ' = d/dt then df'/dg' = df/dg because f' = df/dg g', but if we differentiate f' to g' we implicitly assume that df/dg is independent of g', is it?
  2. jcsd
  3. May 6, 2014 #2
    Perhaps because y and y' are the values of y and y' at the boundaries of a path, in which case they do seem independent.
    Hence a natural follow-up question, instead of binding the positions, why don't we bind the velocities?
  4. May 6, 2014 #3


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