Does the Dot Product of Force and Position Hold Physical Significance?

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SUMMARY

The discussion centers on the mathematical expression derived from differential geometry, specifically the equation \(\frac{d}{dt} \left( \gamma^{i}\frac{\partial\beta}{\partial x^{i}} \right) = 0\), which relates the dot product of position and force to a constant of motion. The scalar field β is interpreted as a potential field, suggesting a connection to physical concepts. However, participants conclude that this relationship lacks practical significance in classical mechanics, with no established connection to the virial theorem or other constants of motion.

PREREQUISITES
  • Understanding of differential geometry concepts, particularly one-forms
  • Familiarity with scalar fields and their applications in physics
  • Knowledge of classical mechanics, including the virial theorem
  • Basic proficiency in vector calculus and dot products
NEXT STEPS
  • Research the implications of one-forms in differential geometry
  • Explore the virial theorem and its applications in mechanics
  • Study the relationship between potential fields and forces in physics
  • Investigate the mathematical properties of constant motion in classical systems
USEFUL FOR

Students and researchers in mathematics and physics, particularly those studying differential geometry and classical mechanics, will benefit from this discussion.

sam guns
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Reason I posted this in the maths help forum is that an equation of this form randomly popped up in a homework I was doing on differential geometry. I started with a one-form ω=dβ (β is a scalar function) and found that if for a random vector v, ω(v) = 0, then

\frac{d}{dt} \left( \gamma^{i}\frac{\partial\beta}{\partial x^{i}} \right) = 0

where γ is the integral curve of v (aka the position if you interpret v as a velocity)

If you interpret the scalar field β as a potential field, then this says that the dot product of position and force is a constant of motion. Understanding it is not really significant to what I am expected to turn in, but regardless, does it have any physical significance?

Homework Statement

 
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welcome to pf!

hi sam! welcome to pf! :smile:

it looks like the formula for a bead sliding along a frictionless rod forced to rotate (irregularly) about a pivot

but, so far as i know, it has no practical significance​
 


Thanks for your reply! It's kind of what I suspected, for a second I thought it could be some important constant of motion related to the virial theorem or something like that, but I couldn't find anything in my old mechanics textbooks. I guess it's just a curiosity then :)
 
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