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Re: [Phys-l] teaching energy

But aren't they really different "flavors"? Kinetic energy is clearly
visible to a student - there's a motion. Even microscopic random thermal KE
can be envisioned by a student. That mental image may not be entirely
correct because of the dependence of KE on v^2, but it is at least a
concrete image.

Potential energies, on the other hand, are way of easily calculating how a
conservative force will change a KE if an object changes position. That is
difficult, if not impossible, for a student to associate with a concrete
image. Without that image, how do you come up with a meaning for "stored".
In what form is it stored. How does it become concrete as KE? I don't think
I really became comfortable with energy until I encountered graduate school
level mechanics and the concepts of action and the Lagrangian.

I also can't imagine how a student forms a concrete image about Conservation
of energy, because it requires a transformation of energy from an entirely
abstract "flavor" (PE) to a concrete "flavor" (KE).

I am not sure when I would even dare to present energy to primary or
secondary level students. Somebody must think they have this all figured out
because it's part of the standards for each grade level.

Bob at PC

-----Original Message-----
From: [mailto:phys-l-] On Behalf Of R. McDermott
Sent: Saturday, September 30, 2006 11:17 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] teaching energy

Bear in mind that we are (mostly) talking about a presentation to high
school students. While what you say is certainly correct, it conveys very
little information to the beginning student that they can use to help them
internalize their learning. By getting them to associate energy with a
location, it is easier for them to deal with TRANSFERS of energy, and with
the concept of working changing the amount of energy, and helps to
the common misconception that energy comes in different flavors; ie, that
is somehow different from PE and has to be "converted" by some unknown and
unspecified process. Beginners (most of them anyway) need a framework
is concrete before they can proceed to abstract.