Re: What is weight? (was Re: Internal or external?)

[Robert Carlson <Raacc@AOL.COM>]

John,

I do appreciate your point.  However, you must remember that there is a large
variation in physics understanding on this list.  I place myself on the lower
level of understanding, but always learning.  When I posed the elevator
problem and asked for the weights, please understand that it was posed as a
Newtonian question.  My concern is that there are teachers reading these
posts who are now confused (as I was when this first went around).  So, in
the Newtonian sense, what is your response to the elevator question?

Thanks,

Bob Carlson

In a message dated 10/10/99 7:17:54 PM Central Daylight Time,
ajmallinckro@CSUPOMONA.EDU writes:

> As I've mentioned in the past when this subject came up, there is a time
>  and a place for everything and the intro course is, IMO, a place to stay
>  pretty squarely in the Newtonian world.  Most engineers (who do indeed
>  comprise the great majority of my students) may never have any genuine
>  need to go beyond that world, although it saddens me to think of such
>  talented folks missing out on the awesome beauty of twentieth century
>  physics.*
>
>  On the other hand, one needn't go out of one's way to use language that
>  will make the ultimate transition from Newtonian gravity to GR a little
>  easier for those who do go on.  The definition of weight is probably one
>  of the best examples of this.
>
>  Students already have experience with the fact that their weight depends
>  on their motion (whether or not they would describe it that way) and it
>  isn't that hard for them to understand the concept of "artificial
>  gravity."  These can be drawn on to help motivate the definition of weight
>  as "what a scale reads" (with the caveat that the scale must exert the
>  only non-gravitational force).
>
>  But my comments in this thread have been directed more to us as teachers.
>  At the very least, I think *we* ought to have a pretty clear understanding
>  of what our best theory of gravitation--now nearly a century old--has to
>  say about the meaning of g.
>
>  John