Re: Absolute or relative space? Newton's Laws

On Feb 21, 10:34 am, mL <mL.bey...@xxxxxxxxxxxxx> wrote:
Androcles skrev:



"Randy Poe" <poespam-t...@xxxxxxxxx> wrote in message
news:5e9f0d11-0af9-4140-8455-4b2faaf28ba2@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| On Feb 21, 1:24 am, proton <leosara...@xxxxxxxxx> wrote:
| > I am reading "The discovery of Dynamics", by Julian Barbour, and I
| > found the following passage:
| >
| > "[Newton] assumed that the forces which act between bodies depend
| > either solely on the relative configuration of the bodies, or else on
| > the relative configuration and the relative velocities of the bodies
| > but in no case on their position or overall velocity in absolute
| > space. [...] This is NOT a consequence of his laws of motion. For
| > example, the strength of the force that acts between two bodies could
| > depend on the velocity of the centre of mass of the two bodies through
| > absolute space without violating any of the three laws of motion."
| >
| > I was very much surprised by this assertion: from Newton's second law
| > F = ma, it is clear that a force can only arise if there is a mass.
|
| Why do you draw that conclusion? That equation doesn't
| say masses cause forces, it says that forces cause masses
| to accelerate.

> | And Newton's law was actually in the form F = dp/dt,
>
> You lying shit, Newton's law was ACTUALLY in the Latin form of:
> "The alteration of motion is ever proportional to the motive force
> impressed; and is made in the direction of the right line in which
> that force is impressed."

Yeah, but do you understand?

*Principia*,DEFINITIONShttp://members.tripod.com/~gravitee/definitions.htm:

" DEFINITION II.
The quantity of motion is the measure of the same,
arising from the velocity and quantity of matter
conjunctly. "

So, [quantity of] motion = (quantity of matter).(velocity),
i.e. momentum in current parlance.

And just to make the matter clearer, in the discussion under
this definition, Newton writes that "motus" is doubled if
you double either mass or velocity, and it is quadrupled
if you double both.

- Randy
.

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