Re: what to call litle "g"

[David Bowman <dbowman@tiger.gtc.georgetown.ky.us>]

John Gastineau wrote:

> The other context is in discussing force, eg, W=mg. It always blows
> away my students when I point out that g is not an acceleration
> here. (In most elementary problems where this first comes up the
> mass is at rest! there's clearly no acceleration.) It is the local
> gravitational constant which has units Newtons/kilogram. Thus, I name 
> g in this context  the "local gravitational constant." 

I agree with John's (and Jim's) complaints here.  I even like the phrase
"freefall acceleration" (although it is somewhat of a mouthful).  However,
the phrase "local gravitational constant" is a little more unwieldy and it is
somewhat of an oxymoron.   The concept of a *constant* is contradicted (or 
at least undermined) by the modifier "local".  If the word "local" must be
used, I think the phrase "local gravitational field" would be more accurate,
especially if the form of g is a vector rather than its scalar magnitude.
I personally prefer the phrase "surface gravity" (which is standard in
planetary science) for the scalar value of g.

Of course, when discussing the equivalence principle, one can just say that -g
(vector) is the local acceleration of the reference frame.

David Bowman
dbowman@gtc.georgetown.ky.us