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Are Lx, Ly, Lz (the components of Angular Momentum)independent to each other?

 
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Apr23-11, 08:35 PM   #1
 

Are Lx, Ly, Lz (the components of Angular Momentum)independent to each other?


In Classical Mechanics, are the three components of Angular Momentum L:

Lx, Ly, Lz

independent to each other?

It seems that there is an identity in Classical Mechanics (Sorry, I can hardly remember where I saw it):

[Li, Lj] = εijk Lk.

Note: [] is Poisson Bracket, εijk is Levi-Civita Tensor

If the identity is true, then the three components of Angular Momentum are not independent to each other.
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Apr23-11, 10:41 PM   #2
 
Angular momenta are independent of each other. Take the obvious case of planar motion in the xy-plane. Then Lx and Ly are zero, and Lz can be anything.
Apr24-11, 03:49 PM   #3
 
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yicong, Of course you are misinterpreting the meaning of the Poisson bracket. Note for example in three dimensions with Cartesian coordinates xi, the Poisson bracket relationship [xi, xj] = 0 for i and j not equal.
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