Re: Calories, calories, & joules

[Hugh Haskell <hhaskell@mindspring.com>]

> On Sun, 14 Sep 1997, Jim Green wrote:
>
> > But in a HS physics class or a college physics class for physicists,
> > chemists, and/or engineers, I think it a disservice to use calories no
> > matter how convenient or entertaining -- "because it is the way we have
> > always said it". As you allude above there are too many things we do because
> > "it is the way we have always done it".  At some point we WILL be using the
> > SI --  Don't we have some modicum of obligation to proselyte it?  For
> > example, it is not too painful to refer to room temperature in oC (or even
> > K) is it?
>
> I think we should demonstrate the advantages of the SI system without
> pretending that those advantages are not often outweighed by other
> factors.  I can't begin to imagine that there will *ever* come a day when
> even scientists--let alone the unwashed masses--will abandon non-SI units.
> What a sad day it will be--and what an enormous step backward--when we
> deny ourselves the use of such meaningful units as the year, the day, the
> astronomical unit, the lightyear, the solar mass, etc.
>
> John
> -----------------------------------------------------------------
> A. John Mallinckrodt      http://www.intranet.csupomona.edu/~ajm
> Professor of Physics    mailto:ajmallinckro@csupomona.edu
> Physics Department       voice:909-869-4054
> Cal Poly Pomona            fax:909-869-5090
> Pomona, CA 91768-4031   office:Building 8, Room 223

Well, John's offhhand remark seems to have opened up a few hidden sores.
Let me weigh in with my idea about units and beginning students.

I start my class with SI units and stick to them throughout. I even
minimize the conversions from cm to m or km, etc. My reasoning is this.
Students who are just starting out in physics are terrified enough without
having to burden them with the problem of continually converting units. I
don't see that as physics and I want them to learn how to do physics and
not unit conversions. The chemists spend way too much time, IMHO, dealing
with both unit conversions and significant figures. Some students I get
after chemistry are so hung up on those two topics that I frequently can't
get them to think about the physics of a problem.

Yes, if they study physics beyond my class, they will eventually have to
deal with the issue of unit conversions, but my contention is that once
they understand the physics of a situation, they can figure out any unit
conversions they need. If they don't understand the physics, then unit
conversions will be just something more they will memorize without the
slightest hint of understanding. And if they forget to do the proper unit
conversions, they will make one of the "embarassing mistakes" that have
been talked about in this thread. One or two of those and they will learn
how to do them before they go public.

Let's not get started on sig figs, shall we?

Hugh

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Hugh Haskell
<mailto://hhaskell@mindspring.com>

The box said "Requires Windows 95 or better." So I bought a Macintosh.
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