In March 2012,
Fernand Brunschwig, Chair, STEMteachersNYC and editor of Robert KarplusÕ
textbook for non-science college students, Introductory Physics: A Model
Approach, posted
the note below to the physics
modeling listserv. In October 2014, he gave me updated URLs, which are here, in
place of the outdated ones.
– Jane Jackson
I quote Fernand
Brunschwig in March 2012.
-------------------------------------------
Energy as the
ability to do work is a definition that is suited for the traditional approach
that makes mechanics the foundation for all of physics, which is what most or
all physics courses do.
At least for a
"liberal arts physics" or a "physics for the general
public," and probably also for a "physics for scientists and
engineers" course, I think, with Richard Muller, that it is better to
start with a more general definition that can more easily be seen to include
thermal phenomena.
In Introductory
Physics: A Model Approach, Ch.
4 ("Matter and Energy"), Robert Karplus begins with "the inherent
power of a material system, such as a person, a flashlight battery, or
rocket fuel, to bring about changes in the state of its surroundings or in
itself." [You can freely read the chapter at http://fernwig.org.
Log in as <guest> and use the password <guest>. JJ]
I also recently
organized and conducted a workshop on teaching energy for PhysicsTeachersNYC
[later called STEMteachersNYC – JJ], for which I developed a series of
energy diagrams that, I believe, would be useful in teaching energy using
Karplus' approach. My idea is that students could be shown one or two of the
simpler diagrams so that they would understand the meaning of the flow arrows
and the way that the before/after bar charts must reflect conservation of
energy, and they could then be asked to complete some of the diagrams with the
energy flow arrows and the levels on the energy bar charts omitted.
Here's the URL
where I've published 4 of the energy diagrams [by 2014, many others too –
JJ]:
1. Ball thrown
vertically:
2. Carry backpack up hill:
3. Person
pushing crate across floor:
4. Car braking
I've created
other diagrams, with and without the arrows and values on the bar charts, which
I could publish if others are interested.
----------------------------------------