Re: [Phys-l] Inertia frame of reference

[John Denker <jsd@av8n.com>]

On 07/28/2009 06:11 PM, carmelo@pacific.net.sg wrote:

> In John Denker's website, he suggests "a freely-falling frame". (It  
> seems to suggest accelerated frame of reference.)

Absolutely not.

First of all, I don't suggest using the term "inertial frame"
at all.  The problem is, it means different things to different
people.  I say this as clearly as I know how at
  http://www.av8n.com/physics/reference-frames.htm

Secondly, according to modern (post-1900) physics, the freely-falling 
frames are unaccelerated, while the laboratory frame is accelerated
... not the other way around.  The laboratory is being accelerated
skyward at about 9.8 m/s/s relative to any nearby freely-falling frame.
It is accelerated by means of contact forces between the laboratory and 
the ground, forces that prevent the laboratory from freely falling.

Feel free to use the laboratory frame if you wish.  It's OK.  Really
it is.

However, please don't call it "inertial".  Arguing about terminology is
usually a waste of time, especially when there are two grossly inconsistent
yet well-established meanings to the term.

The usual good advice applies:  Say what you mean, and mean what you say.
If you mean freely-falling frame, say "freely-falling frame".
If you mean terrestrial lab frame, say "terrestrial lab frame".

Calling one or the other "inertial" adds nothing.