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Re: [Phys-l] Inertia?



I have a different problem with the word "inertia." If you ask someone why a bowling ball rolls down the alley although no one is pushing it, they are liable to say "inertia," in the sense that it is the cause of the continued motion. On those grounds alone I would argue for avoiding it.

joe

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

On Nov 11, 2008, at 3:20 PM, John Denker wrote:

I've got a question: As a matter of good pedagogy, should
we perhaps de-emphasize the whole notion of "inertia" in
favor of more specific notions and conventional scientific
terminology?

As far as I can tell, "inertia" is a non-technical term,
and there is little if anything to be gained by imposing a
technical meaning on it.
The /word/ appears in some technical terms, such as
"moment of inertia" but that is not relevant to the
present discussion.

In the Feynman Lectures on Physics, the term "inertia" appears
once as a phenomenon and once as a physical quantity:
-- As a phenomenon, "inertia" is synonymous with Newton's
first law of motion. Volume I page 2-3.
-- As a physical quantity, "inertia" is synonymous with
mass. Volume I page 7-11.

So my question is, in a technical context, if you mean the
first law of motion, why not just say "the first law of
motion"? Or if you mean mass, why not just say "mass"?

Of course in a non-technical context, it's perfectly OK
to use non-technical terms.

Also, I'm not allergic to /mentioning/ a non-technical term
... provided it is merely mentioned and not emphasized.

This whole thread worries me, because it seems to give too
much emphasis to "inertia". It seems to delve into fine
points that were never worth delving into.

=====

The same pedagogical point arises in connection with other
terms:
Example: "blue" is a qualitative term. It is not worth
delving into the fine points of "blue", because if you
were trying to be quantitative you would use other terms
and other concepts, such as wavelength.
Example: "heat" is not easy to define in a useful way. It
is not worth starting a holy war over the definition of
"heat", because if you were trying to be quantitative you
would use other terms and other concepts, such as energy,
entropy, and/or temperature.

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