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Lagrangians and PConservation 
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#1
Oct1906, 02:30 PM

P: 21

I have a problem with a particle experiencing a central force towards some origin, as well as a gravitational force downwards. I've calculated the Lagrangian, and the equations of motion. Now I'm being asked to see if the system follows conservation of angular momentum. How do I do this? I know it has something to do with seeing if the system is invariant of rotation, but how do I check for that?



#2
Oct1906, 10:11 PM

P: 214

If [tex]\frac{\partial L}{\partial q} =0[/tex] then the conjugate momentum [tex]\frac{\partial L}{\partial \dot{q}}[/tex] is a conserved quantity.
If that doesn't clear things up, then post what you have for the Lagrangian. 


#3
Oct2006, 02:12 AM

P: 138

But the conjugate momentum is the same as the angular momentum only in some cases.
Compute H and chech if H commutes with J. 


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