Examples of a Lagrangian

  • #1
JTC
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Assuming generlized variables, q, we have a Lagrangian in mechanics as the kinetic energy, K, minus potential energy, U, with a dependency form such that

L(q,dq/dt) = K(q, dq/dt) - U(q)

Can someone provide examples of Lagrangians in other disciplines?
 

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  • #2
PeroK
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What do you mean by other disciplines?
 
  • #3
JTC
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What do you mean by other disciplines?
I VAGUELY recall a Lagrangian in particle physics that was about a page long.

Just other examples of Lagrangians...
 
  • #5
  • #6
jtbell
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I VAGUELY recall a Lagrangian in particle physics that was about a page long.
An example of a much simpler Lagrangian of that type, which is often taught as a stepping-stone to quantum field theory:

Classical Scalar Field in Four Dimensions

Here we use not the Lagrangian of an entire system, but rather the Lagrangian density at each spacetime point.
 

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