Re: Swartz letter in AJP (work-energy theorem)

[Hugh Logan <hloganPHY@CFL.RR.COM>]

Brian Whatcott wrote:

> At 06:45 AM 9/1/2004, you wrote:
>
> > /// I am reminded
> > of a somewhat similar confusing item in the high school text,
> > _Foundations of Physics_,
> > 2nd ed, by Lehrman and Swartz. On p.45 of the _Teacher's Guide_ for that
> > text, one finds
> > "The cavalier way in which we treat the difference in definition of
> > speed and velocity is
> > very deliberate. It is a reaction to certain situations in our own
> > experience where knowledge
> > of the defined difference became  the essential feature of motion study
> > to be tested with
> > true-false questions."
>
>
> ////
>
> > I would have forgotten this, except for the fact that, back in 1970, I
> > quoted L&S's description of their treatment of velocity and speed as
> > "cavalier." One of the students, a grandson of a famous person that
> > everyone on this list would recognize, asked what "cavalier" meant. That
> > caused me more difficulty than the physics, although I knew what was
> > meant from the context.
>
>
> ///
>
> > Hugh Logan
> > Retired physics teacher
>
>
> I can see why the quoted use of "cavalier" led to student difficulty.
>  It means quite the opposite of the writer's intended value, where
> cavalier is "off-hand, curt, supercilious" [COD]

However, I thought Lehrman and Swartz's usage might fit in with one of
the M-W (online) dictionary entries for "cavalier" used as an adjective:
"marked by or given to offhand and often disdainful dismissal of
important matters" -- perhaps with the emphasis on "offhand" rather than
"disdainful." The reader of the text (not the _Teacher's Guide_ in which
the intent is "deliberate") might think the important matter of the
distinction between speed and velocity has been dismissed in an offhand
manner. In 1970, I could only think of a gentleman on a horse, perhaps
disdainful of those beneath him. I remained silent rather than display
further ignorance. In the AJP article, Cliff Swartz wrote, "You don't
plug friction into the wall socket or feed it gasoline or steak.
Certainly it cannot do negative work, a concept that can only bewilder
the innocent." Is Swartz being "cavalier" in his dismissal of negative
work, while admitting that
(if I interpret him correctly) juniors might use it?

Hugh Logan
Retired physics teacher