Re: [Phys-l] Inertia frame of reference

[chuck britton <cvbritton@embarqmail.com>]

I believe these definitions have more of a metaphysical meaning than  
an operational one.


On Jul 28, 2009, at Jul 28(Tue) 9:58 , John Mallinckrodt wrote:

> Even supposing that there really were such things as "fixed stars,"
> it seems to me that it would be literally impossible in practice to
> determine in a finite time whether or not one is moving at constant
> velocity with respect to them.  Am I wrong?
>
> John Mallinckrodt
> Cal Poly Pomona
>
> On Jul 28, 2009, at 6:46 PM, chuck britton wrote:
>
> > Absolutely no claim of being the BEST definition - but an oldie and
> > goodie is one that is at rest (or moving at constant velocity) wrt
> > the 'fixed' stars.
> > Of course we know that there ARE no 'fixed' stars - but hey - it
> > gives a starting point to argue from.
> >
> > Denker's 'unrestrained' free-fall frame is the modern choice of
> > General Relativists.
> > You might not want to say that this would be a frame that is
> > 'accelerated' by the force of gravity - since general relativity sez
> > that there IS no 'force of gravity'.
> >
> > You may not be quite ready to teach intro physics from a General
> > Relativity POV. At least I HOPE you're not ;-)
> >
> > Use what works for you - and the smart kids will figure it out
> > without suffering from too much lasting damage.
> >
> > On Jul 28, 2009, at Jul 28(Tue) 9:11 , carmelo@pacific.net.sg wrote:
> >
> > > Hi everyone,
> > >
> > > Does anyone know which is the best definition on inertia frame of
> > > reference?
> > >
> > > Ohanian defines "inertial reference frame" as a frame in which
> > > Newton’s
> > > laws of motion are valid to a first approximation.
> > > Ludwig Lange argued that any three material points simultaneously
> > > projected from a single point, and moving freely in noncoplanar
> > > directions, constitute an inertial system.
> > > In John Denker's website, he suggests "a freely-falling frame". (It
> > > seems to suggest accelerated frame of reference.)
> >
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