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[Phys-L] Re: Energy is primary and fundamental?



Some of the posts under this topic have implied or outright stated that
teaching about energy can be easier, and can lead to more physics
understanding, than teaching about acceleration.

I am not here to debate that issue, but I would like to point out one
advantage of trying to teach acceleration (even in general-education
science courses). Acceleration is a physical example of the second
derivative, or in non-calculus terms... the rate of change of a rate of
change. This is a very difficult concept. Even USA presidents, cabinet
members, and advisors have goofed-up this concept when talking about
things like the rate of change of the rate of inflation.

I have been told by economics professors at my institution that they can
tell which students in their classes have already taken the Bluffton
University physical science course because the students have had a lab
experience dealing with acceleration. This means they come into
economics class with some concept of the rate of change of a rate of
change.

Of course we can debate who should go first... where should the
second-derivative concept be first taught? Math class is obvious.
Economics/business might be suggested. However, in physics we can
easily go into the lab and do a physical experiment. Math professors I
know have always envied the lab experiences physics students have with
calculus and statistics concepts. I've already mentioned what the
economists say.

Until this year, every Bluffton student did an air-track experiment to
learn about velocity and acceleration. That amounted to about 250
students a year doing this experiment. Of course, some never understood
it, but many did; at least half did; maybe 75%... and that makes a
difference in public understanding of this concept.

Non-science professors have also noted that students who already had
gen-ed science write better and more logically because we have always
required weekly lab reports from all students.

The sad thing at Bluffton is that the faculty changed the science
requirement from two semesters of lab science to one semester of lab
science plus one semester of non-lab science. This means perhaps half
the students will take physical science without lab. I am convinced the
loss is a far greater loss than just the loss of science
content/experience.

Conclusion... We not only need to consider the best way to teach
physics, we also need to consider what students learn from physics class
beyond physics. Then, we need to decide which trade-off is the better
trade-off. If we concentrate more on energy and less on forces and
acceleration, the increased energy awareness is certainly good and has
ramifications beyond physics class. But the loss of acceleration
experience also goes beyond physics, and my non-physics colleagues have
made me aware of this.


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu