What do you do when time is present in Lagragian Equation?

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    Lagragian Time
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Homework Help Overview

The discussion revolves around the application of Lagrangian mechanics in scenarios where time is explicitly present in the equations. Participants are exploring how to approach Lagrangian equations that incorporate time, contrasting their understanding with cases where time is absent.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants express uncertainty about how to handle time in Lagrangian equations, with some seeking clarification on the relevance of time during differentiation. There are references to specific examples and methods, as well as questions about the implications of time-dependent variables.

Discussion Status

The discussion is active, with participants sharing their thoughts and questioning the role of time in the differentiation process. Some guidance has been offered regarding the treatment of time-dependent terms, but no consensus has been reached on a definitive approach.

Contextual Notes

Participants are working under the constraints of their current understanding of Lagrangian mechanics and are referencing specific examples to support their inquiries. There is an acknowledgment of differing interpretations regarding the handling of time in the equations.

superpig10000
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I set up a Lagragian equation that involves time t. What do I do? I only know how to solve Lagragian equation in the absence of time. Please help.
 
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superpig10000 said:
I set up a Lagragian equation that involves time t. What do I do? I only know how to solve Lagragian equation in the absence of time. Please help.
Here is one example. If you can justify the throw-away in section 1.3, perhaps you can do something similar.

http://physics.technion.ac.il/~avron/classical-mechanics/kapitza-wbct.pdf
 
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I understand the throw away, but when I differentiate

dL/dq - d/dt (dL/dq dot) = 0

do I care about time at all?
 
superpig10000 said:
I understand the throw away, but when I differentiate

dL/dq - d/dt (dL/dq dot) = 0

do I care about time at all?
If your (dL/dq dot) is a function of time, then why would you not care? I think once you have the simplified Lagarangian you do what you always do. It's been a long time since I did this stuff, but I don't see any reason to deviate from the example.
 

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