Poisson brackets little problem

In summary, the question is asking to calculate the Poisson brackets formed by the Cartesian components of linear momentum and angular momentum, as well as the Cartesian components of angular momentum. The formula for calculating these brackets is given, and the attempted solution includes calculating the Cartesian components of M and p. The subscript for the Poisson brackets is always q,p. The formula for calculating the brackets is provided, using the Einstein summation convention.
  • #1
fluidistic
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Homework Statement


For a particle, calculate Poisson brackets formed by:
1)The Cartesian components of the linear momentum [itex]\vec p[/itex] and the angular momentum [/itex]\vec M =\vec r \times \vec p[/itex].
2)The Cartesian components of the angular momentum.

Homework Equations



[itex][u,p]_{q,p}= \sum _k \left ( \frac{\partial q }{\partial q_k } \frac{\partial v }{\partial p _k} -\frac{\partial q }{\partial p_k } \frac{\partial v }{\partial q _k} \right )[/itex].

The Attempt at a Solution


2)Nothing still, waiting to complete 1).
1)I calculated the Cartesian components of M and p.
I don't understand what I have to calculate. [itex][\vec p, \vec M][/itex] I'm guessing but with what subscript?
Thanks for any help.

Edit: Hmm I think the subscript is always q,p. But p and M are vectors, so have I to calculate directional derivative?
 
Last edited:
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  • #2
[tex] \vec{p} = ( p_x , p_y , p_z ) = p_i [/tex] and [tex] \vec{r} = ( x , y , z ) = x_i [/tex]

[tex] M_i = \epsilon_{ijk} x_j p_k [/tex] where the einstein summation convention is used

[tex] [p_i,M_j]= \sum _l \left ( \frac{\partial p_i }{\partial q_l } \frac{\partial M_j }{\partial p _l} -\frac{\partial p_i }{\partial p_l } \frac{\partial M_j }{\partial q _l} \right ) [/tex]

hope this helps
 

Related to Poisson brackets little problem

What is a Poisson bracket?

A Poisson bracket is a mathematical concept used in classical mechanics to describe the relationship between two physical quantities, such as position and momentum, at a given point in time.

How is a Poisson bracket calculated?

A Poisson bracket is calculated by taking the partial derivatives of the two quantities with respect to the canonical variables, and then multiplying them together and taking the difference.

What is the significance of the Poisson bracket in physics?

The Poisson bracket is significant because it allows us to describe the time evolution of a physical system and make predictions about its behavior.

What is the Poisson bracket little problem?

The Poisson bracket little problem refers to a specific scenario in which the equations of motion for a physical system can be simplified using Poisson brackets.

Can the Poisson bracket be extended to quantum mechanics?

Yes, the concept of a Poisson bracket can be extended to quantum mechanics, where it is known as a commutator. However, the mathematical calculations and interpretations may differ from classical mechanics.

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