Can Newton's Method Solve Freer Motion?

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Discussion Overview

The discussion revolves around the applicability of Newton's method versus Lagrangian mechanics in solving equations of motion, particularly in the context of free motion without constraints. Participants explore scenarios where one approach may be favored over the other.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions whether there are cases where Newton's method is necessary while Lagrangian mechanics cannot be applied, suggesting that this might occur in scenarios of totally free motion.
  • Another participant challenges the terminology used, asking for clarification on what is meant by "Lagrange 1 and 2," and asserts that the solvability of equations of motion does not depend on the theoretical framework used to derive them.
  • A third participant provides clarification on the terms, indicating that "Lagrange 1" refers to the use of Lagrange multipliers for holonomic constraints, while "Lagrange 2" involves generalized coordinates.
  • Another participant argues that Lagrangian mechanics is applicable even in the absence of constraints and suggests it may facilitate deriving constants of motion, while noting potential complications with dissipative forces like friction.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of Lagrangian mechanics in systems without constraints, with some asserting its effectiveness while others question the necessity of Newton's method in such cases. The discussion remains unresolved regarding the conditions under which each method is preferable.

Contextual Notes

There are unresolved assumptions regarding the definitions and implications of "Lagrange 1 and 2," as well as the impact of dissipative forces on the applicability of the discussed methods.

Juli
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Hello everyone,

my question is, if there is a case, where you can't you Langrange (1 or 2) but only Newton to solve the equation of motion?
My guess is, that it might be, when we have no restrictions at all, so a totally free motion.
Does anybody know?
 
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What do you mean by Lagrange 1 and 2? That does not seem like standard nomenclature to me. Please be specific.

Generally, the equations of motion are differential equations and whether they can be solved or not does not depend on the theory you used to derive them. Where you could fail is in arriving at a set of equations of motion.
 
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Usually "Lagrange 1" is the formulation with the (holonomic) constraints treated with Lagrange multipliers, while "Lagrange 2" is the formulation in terms of an appropriate set of "generalized coordinates".
 
Regardless, it should probably be pointed out that Lagrange mechanics is perfectly applicable to systems without constraints. It could even be argued it does better in ease of deriving constants of motion etc. Where you can run into issues is when there are dissipative forces (eg, friction) acting on the system.
 
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