Is there some geometrical interpretation of force from Newton's Laws?

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The discussion explores the relationship between force, momentum, and energy within the framework of Newton's Laws, specifically through the equations dP = F dt and dE = F dr. It raises questions about the definition of force and the potential for a geometrical interpretation, noting that momentum and energy, while conserved in closed systems, behave differently when net forces are applied. The distinction between the time dependence of momentum and the distance dependence of energy is emphasized, highlighting that they are not interchangeable. Additionally, the conversation touches on the formalism of (dP, dE), suggesting a resemblance to four-vector concepts in special relativity, while cautioning against conflating Newtonian and relativistic frameworks. The importance of understanding conservative forces in relation to potential energy gradients is also noted.
OlegKmechak
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dP = F dt
dE = F dr

or if we introduce ds = (dt, dr)

(dP, dE) = F ds

And both dP and dE are constant in closed system.

Some questions:
- How does its implies on definition of Force?
- Is there some clever geometrical interpretation of Force?
- Why P and E seems almost interchengable?
 
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Both momentum and energy are conserved in a closed system, but if we’re applying a net force to an object it’s not a closed system. The dP and dE equations tell us how the momentum and energy change in this non-closed system as a result of applying the force.

A quick look at the equations will tell you that the change in energy is proportional to the distance across which the force is applied while the change in momentum is proportional to the time the force is applied; they are different things not interchangeable. The difference will be more apparent if you write the equations out more precisely to reflect that ##P## and ##r## are vectors while ##E## and ##t## are scalars.

And what is that (dP,dE) formalism in the third equation? It looks like the four-vector formalism of special relativity? If that’s what it is, you might want to hold off on that until you’ve thoroughly nailed down your understanding of the Newtonian model.
 
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Force is the gradient of the potential energy. Working in one dimension, we have F = -dU/dx. The rate of change of potential energy with time is

$$\frac{dU}{dx} \frac{dx}{dt} = -Fv$$

The rate of change of kinetic energy T is

$$\frac{d}{dt}\frac{1}{2}mv^2 = \frac{dT}{dv} \frac{dv}{dt} =mv \frac{dv}{dt} = mva$$

Because energy is conserved, the change in kinetic energy must compensate the change in potential energy, so we must have Fv = mva, i.e. we have

$$F = ma$$
 
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love_42 said:
Force is the gradient of the potential energy.
This is only true for conservative forces, not for all forces.
 
Nugatory said:
And what is that (dP,dE) formalism in the third equation? It looks like the four-vector formalism of special relativity? If that’s what it is, you might want to hold off on that until you’ve thoroughly nailed down your understanding of the Newtonian model.
In special relativity time and space are same things(with precission to signature). So from this point of view momentum P and energy E are same things(vector in 4-d space) or isn't it?
Sory, it is hard to me to explain what I want to find out :) I will take a little break
 
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