Relationship between Lagrangian and Energy

Click For Summary
SUMMARY

The relationship between the Lagrangian and energy in classical mechanics is defined by the equation E = Σ(Vi * ∂L/∂Vi) - L for time-independent potentials. When dealing with time-dependent potentials, the relationship modifies to total dE/dt = -∂L/∂t. This confirms that energy conservation principles still apply, albeit with adjustments for time dependencies. Textbooks such as "Mechanics" by Landau and Lifgarbagez may not cover this derivation explicitly.

PREREQUISITES
  • Understanding of Lagrangian mechanics
  • Familiarity with classical mechanics principles
  • Knowledge of time-dependent and time-independent potentials
  • Basic calculus, particularly differentiation
NEXT STEPS
  • Research the derivation of energy conservation in Lagrangian mechanics
  • Explore advanced textbooks on classical mechanics beyond Landau and Lifgarbagez
  • Study the implications of time-dependent potentials in physics
  • Learn about the Hamiltonian formulation of mechanics
USEFUL FOR

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

theneedtoknow
Messages
169
Reaction score
0
I know that, for time-independent potentials, we have E=sum (Vi*partial dL/dVi) - L
What if one or more of the potentials are time-dependent?
Is the relationship between energy and the lagrangian then "total dE/dt = - partial dL/dt "?
 
Physics news on Phys.org
Thank you! Would you happen to know of any textbooks where this is derived? I have the Landau and Lifgarbagez "Mechanics" one and they do not do so.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 19 ·
Replies
19
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
9
Views
2K
  • · Replies 27 ·
Replies
27
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K