Re: [Phys-l] "Flow"

[Larry Smith <larry.smith@snow.edu>]

At 9:08 PM -0600 5/18/06, JMGreen wrote:
> I must confess that the recent "flow" discussions caught me me by
> surprise.  I would like  to explore my understanding of how others
> use the term ...
>
> Consider the Joule Mechanical Equivalent of Heat experiment:
>
> Which of you would prefer to think of the process as follows:
>
> The Earth does work on the weights as they fall.
> The weights do work on the strings.
> The strings do work on the paddle wheel.
> The paddle wheel does work on the water molecules.
> The average KE of the water molecules increases.
> The temperature of the water increases.

I prefer this last explanation.

My concern about momentum|heat|energy flow is that intro students might
think that it does mean there is a fluid corporeal substance moving.

If JD carefully explains that the blue bicycle is different from the red
bicycle, and if he gets good results...I find it hard to argue with good
results from the students.

But I also think it is difficult to guess what is in students' minds until
someone does the research.  Educational research can produce very
surprising results.

I don't mind if JD or the community of physicists define "flow" to apply to
things like momentum, but until the research is done it isn't clear that it
benefits intro students, especially when in their prior experience "flow"
means a fluid.

Larry