Re: is free-fall an inertial frame?

[Stefan Jeglinski <jeglin@4PI.COM>]

> 1) Newtonian response:

<snip>


> In this paradigm, an object in free fall at the earth's surface is
> impelled by the gravitational force of the earth.  In searching for an
> inertial frame, this force must be taken into account.

As you mentioned, in searching for an inertial frame, we look for a
way to write F=ma. If we choose rotating frames, we quickly run into
problems doing this. But it is easy enough to find a frame in which
we can write F=mg.


> 2) GR response:
> You are entirely correct;  there is no "real" gravitational force;  only
> "real" forces must be removed to experience force free motion. (But then
> things are not so simple as in the F=ma paradigm.)


Yes, I seem to understand the GR situation much better (oddly in my
estimation). I wonder why in searching for an inertial frame in the
Newtonian response, free-falling frames are ignored or avoided (see
my response to John Denker's post). There would not appear to be the
same basis for "avoidance" of a free-fall as for a rotating frame,
when trying to find an inertial frame.


Stefan Jeglinski