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



Van Heuvelen does the same with bar graphs in the Alps pages. Seems to
me the pie charts have the nice addition of built in conservation is
you equate area with energy.

cheers,
joe
On Aug 11, 2005, at 10:18 AM, John Barrer wrote:

--- "R. McDermott" <rmcder@PEOPLEPC.COM> wrote in
part:
SNIP

What is NOT silly, imo, is beginning
to introduce the idea of
energy transfer, energy balance, etc - The concepts,
not the math. The math
can come in later. My students have no problem
"getting" that energy can
transfer from one "object" to another, and that the
total energy should
remain constant as long as additional objects are
not interfering. SNIP

A very nice, concrete way to deal with this is through
the use of energy pie charts. Specify the system and
then change the sizes of the "energy slices" (KE, grav
pot, elastic, etc) as the changes occur within the
system. As long as no external force(s) interact with
the system, the size of the pie remains constant. This
requires NO computations but it does demand
conceptrual understanding. BTW, at least initially it
is helpful to always include Earth in the system so
there is no energy transfer in/out, keeping the pie
diameter constant.

I have found that introducing energy concepts via pie
charts well before any energy computations (and in
parallel with traditional kinematics) really helps
students' conceptual understanding.
John Barrere


Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556