Re: what to call little "g"

["Paul Camp" <pjcamp@coastal.edu>]

> It has to be short. It has to be manifestly obvious what we're 
> talking about, and freshmen and younger must understand it. For that 
> reason I'm very uncomfortable with the word "field," for that's a 
> very subtle concept. As I said in my first post, there seem to be two 
> common uses for the symbol "g" that are mutually exclusive in 
> phraseology. One is the field strength (you physicists know just 
> what I mean, but our students will not) and the other is the 
> acceleration of an object in freefall. 

> John E. Gastineau

I don't see why this is a problem. Yes, "field" is a rather subtle 
concept but that simply means that it is probably a good idea to 
introduce it early and keep cycling back to the notion. It makes less 
sense, to me, to wait until the middle of the second semester to 
introduce a subtle concept, giving them less time to live with the 
idea.

A parable: consider a field of grass which contains a water hose and 
a grasshopper. The blades of grass near the hose will grow taller 
near the water hose because they get more nourishment. The 
grasshopper jumps from blade to blade through the field. The height 
of the grasshopper depends on the amount of water coming out of 
the hose. However, the grasshopper never has to know anything about 
the hose because it only ever interacts with the blade of grass. So 
the grass transmits the interaction between the grasshopper and the 
water hose.

It seems to me that is a pretty good first pass at the field concept 
-- map the hose and grasshopper onto the interacting particles and 
the the grass onto gravity. I don't really see the point in putting 
that off, especially since, as you note, the alternatives are 
uniformly dreadful.

Paul J. Camp                   "The Beauty of the Universe
Assistant Professor of Physics  consists not only of unity
Coastal Carolina University     in variety but also of 
Conway, SC   29528              variety in unity.
pjcamp@csd1.coastal.edu             --Umberto Eco
pjcamp@postoffice.worldnet.att.net    The Name of the Rose
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