Lagrangian vs Hamiltonian Mechanics

Abide By Reason
Sep 26, 2025
5 notes
5 Notes in this Video

Lagrangian and Hamiltonian Mechanics as Dual Analytic Formulations

AnalyticalMechanics LagrangianMechanics HamiltonianMechanics
02:00

Abide by Reason frames Lagrangian and Hamiltonian mechanics for learners who have seen Newton’s force laws and energy conservation but not the analytic reformulations based on scalar quantities.

Legendre Transform as Bridge Between Lagrangian and Hamiltonian

LegendreTransform LagrangianToHamiltonian DualDescriptions
10:00

This note is for learners trying to understand the mathematical relationship between (L(q,\dot{q})) and (H(q,p)), beyond memorizing the formula (H = p\dot{q} - L).

Generalized Momentum Beyond mv and Relativistic Example

GeneralizedMomentum RelativisticMechanics NonNewtonianMomentum
17:00

Abide by Reason addresses the misconception that momentum is always (p = mv), showing how generalized momentum arises from the Lagrangian.

Hamilton’s Equations, Phase-Space Flows, and Energy Level Curves

HamiltonsEquations PhaseSpace EnergyLevels
22:30

Abide by Reason explains Hamilton’s equations and phase-space geometry for learners moving beyond configuration-space pictures.

When to Prefer Lagrangian vs Hamiltonian Formulations in Practice

MethodChoice AnalyticalTradeoffs NumericalConsiderations
28:00

Abide by Reason offers practical guidance for students deciding which analytic framework to use on real mechanics problems.