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Re: PHYS-L Digest - 8 Oct 1999 to 9 Oct 1999 - Special issue

Leigh Palmer <palmer@SFU.CA> wrote:

The combined mass in the Atwood's machine moves in the direction of
the net force;
it can be treated, mathematically, as if it were moving along an
axis.

[deleted]

You will not help the students by likening this to a one particle
system.

In a first year college-level mechanics course, I wouldn't treat the
Atwood machine as a one-particle system the first time we discuss it.
But I might bring it up later in the course when we discuss motion of
the center-of-mass as a way to tie what they do (or should) know with
the new material. I also do this when I show them how the equations
for free-fall motion can be derived from the work-energy theorem for
gravity.

I think it is good pedagogy to show how physics is a consistent
theoretical system and that a correct answer can be found by more than
one path. The less adept students can always rely on the path with
which they are most comfortable; the more advanced students begin to
appreciate the beauty of the theoretical system.

Glenn A. Carlson, P.E.
St. Charles County CC
St. Peters, MO
gcarlson@mail.win.org

"Confidence is a greater motivator than need."