Can you find two different constants by Noether's theorem

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Homework Help Overview

The discussion revolves around a problem in Classical Dynamics, specifically related to Noether's theorem and symmetries in a 3-dimensional one-particle system with a potential energy expressed in cylindrical polar coordinates. The original poster seeks to identify multiple symmetric transformations for the system.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster has identified one symmetric transformation and is seeking assistance in finding another. Some participants question the existence of an additional transformation, while others suggest exploring time symmetries in addition to spatial ones.

Discussion Status

The discussion is ongoing, with participants sharing hints and exploring different approaches to the problem. There is no explicit consensus on the number of transformations, but guidance has been offered regarding the consideration of time symmetries.

Contextual Notes

Participants note that the problem is sourced from a specific textbook, which may imply certain constraints or expectations regarding the solutions. There is also a reminder of the forum's policy against providing direct answers, emphasizing the learning process.

qinglong.1397
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Homework Statement



Consider a 3-dimensional one-particle system whose potential energy in cylindrical polar coordinates [tex]\rho[/tex], [tex]\theta[/tex], z is of the form V([tex]\rho[/tex], k[tex]\theta[/tex]+z), where k is a constant.

Homework Equations


The Attempt at a Solution



I already find a symmetric transformation:
[tex]\rho '[/tex]=[tex]\rho[/tex], [tex]\theta '[/tex]=[tex]\theta[/tex]+[tex]\theta_0[/tex], z'=z-k[tex]\theta_0[/tex].

Can you help me find at least another one? Thank you!
 
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No body can do it?
 
For starters, are you sure there is another one?
 
And what have you done on the problem? It is strictly against policy to just hand out answers -- it's cheating and does little to help the student learn.
 
Hurkyl said:
And what have you done on the problem? It is strictly against policy to just hand out answers -- it's cheating and does little to help the student learn.

I found one solution, as mentioned in the first post. I just do not know how to find the other one. I need your help. Just hint. Thanks!
 
This is a problem from Classical Dynamics: A contemproray approach by Jose. I think it is not very possible that it is wrong.
 
Ah yes... problem 3.11 by any chance? Now that you mention it, I remember doing that one for a homework assignment once upon a time :wink: and I seem to remember having the same difficulty with it.

Try thinking about symmetries in time, since you've already considered the three spatial coordinates.
 
diazona said:
Ah yes... problem 3.11 by any chance? Now that you mention it, I remember doing that one for a homework assignment once upon a time :wink: and I seem to remember having the same difficulty with it.

Try thinking about symmetries in time, since you've already considered the three spatial coordinates.

Oh, yeah. I never thought about that. Thank you very much!
 

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