I myself have sometimes thought of it this way, but I have never expressed
it so clearly, nor have I communicated with my students using these words.
I intend to try this description with students to see what happens.
I certainly think Larry Smith is making a good point when he asks, perhaps
rhetorically, if flow typically conjures up thoughts of "stuff flowing" in
the minds of our students. There is no question that it does, and this is
why we need clear alternative wording like John is trying to provide.
In addition to words, we also need physical models that are easily
understood. One demonstration I like is the row of dominos that topple over
one by one. This is a macroscopic and very clear demonstration of something
propagating from one place to another without the actual stuff moving (very
far). I like to have students argue/discuss what exactly is moving or
flowing in this demonstration.
The domino example might be more appropriate for sound propagation than for
generalized energy flow, but it is a good example something moving from one
place to another without actually moving stuff from one place to another.
Unfortunately I am coming up a little short in terms of making the domino
demonstration seem overall congruent with John's definition of flow. If we
view each domino toppling into the next we have the flow of energy described
above, so the picture is congruent in a step-by-step fashion, but if we view
the overall event I think students will lose the idea of balance and
simultaneity.
Can anyone think of good ways to describe the domino example? Does anyone
use other demonstrations of flow where we visually see something flowing but
obviously realize matter itself is not flowing?
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817