Equation of motion from Hamiltonian

Click For Summary
SUMMARY

The discussion focuses on deriving the equations of motion from the Hamiltonian, specifically using the Hamiltonian function H defined as H=∑^N_{i=1}(p_i^2/2m + 1/2(x_{i+1}-x_i)^2 + (1-cos(2πx_i))). The Hamilton equations of motion are presented as dot{q} = ∂H/∂p and dot{p} = -∂H/∂q. The participants emphasize the importance of checking dimensions for consistency in the derived equations, particularly when substituting mass m=1 into the equations.

PREREQUISITES
  • Understanding of Hamiltonian mechanics
  • Familiarity with partial derivatives
  • Knowledge of classical mechanics concepts, particularly equations of motion
  • Ability to analyze dimensional consistency in equations
NEXT STEPS
  • Study Hamiltonian mechanics in detail, focusing on the derivation of equations of motion
  • Learn about dimensional analysis and its application in physics
  • Explore examples of Hamiltonian systems with identical particles
  • Investigate the implications of potential energy terms in Hamiltonian formulations
USEFUL FOR

Students and researchers in physics, particularly those studying classical mechanics and Hamiltonian dynamics, will benefit from this discussion.

LagrangeEuler
Messages
711
Reaction score
22

Homework Statement


H=\sum^N_{i=1}(\frac{p_i^2}{2m}+\frac{1}{2}(x_{i+1}-x_i)^2+(1-\cos(2\pi x_i))

Homework Equations


Hamilton equation of motion I suppose
##\dot{q}=\frac{\partial H}{\partial p}##
##\dot{p}=-\frac{\partial H}{\partial q}##[/B]

The Attempt at a Solution


If particles are identical then
##\dot{p}=m \dot{x}##
So if I understand well I will get from here system of equations
##\dot{p_1}=-\frac{\partial H}{\partial x_1}##
If I take for example m=1, then
##\dot{x_1}=-\frac{\partial H}{\partial x_1}##
Is this correct?
 
Physics news on Phys.org
no. Check the dimensions.
 
Ok. Can I get some help?
 
Yes: write down the dimensions and check,
 
In particular I think BvU is trying to draw your attention to the partial derivatives you wrote in your last statements. Check those dimensions to see if they are consistent with the definitions you wrote in the relevant equations section.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
Replies
7
Views
6K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
7
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 11 ·
Replies
11
Views
3K
Replies
6
Views
3K
  • · Replies 15 ·
Replies
15
Views
2K