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Re: Energy



I'll go even farther. Is it really so terrible if students coming out of an
Introductory AND Terminal physics course have a 'fluid flow' vision of
energy? Such a vision will work well enough for them in their everyday
lives and is (hopefully) a _more_ accurate and useful model than they
probably had before taking the course.

I will continue to contend that students who go on to higher level courses
in physics SHOULD have the intellectual tools to move beyond early,
simplified, and often inaccurate models to a more sophisticated
understandings. Can we really get across the more abstract models of energy
to students who can't always grasp velocity and acceleration after 1/2 a
semester of intensive work on those topics? I'm not saying 'teach energy
and heat as a fluid flowing', but if that is the image that some student
come away with, that may not really be so awful. ;-)

Rick

**********************************************
Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556
rtarara@saintmarys.edu

FREE PHYSICS INSTRUCTIONAL SOFTWARE
www.saintmarys.edu/~rtarara/
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----- Original Message -----
From: "Michael Edmiston" <edmiston@BLUFFTON.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, September 21, 2001 8:23 AM
Subject: Re: Energy


Several times we have lamented that the word "flow" is apt to be construed
as flow of something material or of some sort of fluid. Brian McInnes
said
this quite well when he stated... "I believe its use carries the
pedagogical
danger that our students, especially at an introductory level, move simply
and quickly from the word flow to the misconception that the property
flowing is a fluid. In the everyday world of these students things that
flow are fluids and fluids are stuff."

I wonder if this is too pessimistic. Certainly some students get this
goofed up, but the physics definition of flow is not the only one that
does
not involve fluid. There are a several definitions of flow in the
Merriam-Webster Dictionary that do not involve fluid or transfer of
matter.
The examples given are not physics examples. One definition is...

to derive from a source... "the wealth that flows from trade"

Another is...

to proceed smoothly and readily... "conversation flowed easily"

For sure, students are not always aware of various definitions of common
words. But the examples above demonstrate that we physicists are not the
only ones using flow in a way that does not involve fluids. Students
certainly hear and read about the types of flow described above and I
don't
think it bothers them. Therefore I would say that an educated public, or
at
least a public that wants to be educated, shouldn't have problems once we
explain that flow of energy does not necessarily involve the flow of some
sort of fluid.

Of course, one problem with the physics of thermal energy is that
sometimes
it does involve fluid. The thermal energy made available in my furnace
gets
to my bedroom because I have water flowing in pipes between my furnace and
my bedroom. But I repeat that a public wanting to be educated ought to be
able to figure this out. If students have problems with this, I don't
think
it's a problem with words, I think it's a problem with desire.

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