Re: No definition of weight

[Bernard Cleyet <anngeorg@PACBELL.NET>]

I think the words weight and light are similar and the arguments pro and con
for their use in teaching are similar.  This thread illustrates why, I think,
a dose of philosophy is necessarily concomitant with the teaching of Physics.
A familiarity with the terms, schools, people, etc. e.g. idealism, Berkeley,
Vienna, operational, reification, etc. is useful.

As I've written in another thread, we live in a lay world.  Pointing out the
"errors" of lay use of physics terms can serve to make more clear the physics.

In answer to LH, when everyone has taken Physics, yes -- We will all say "I
over ate yesterday and as a result my mass has increased, such that the earth
(less its rotation, etc.) attracts me with an increase of ten newtons."

bc, who's still not very clear.



Laurent Hodges wrote:

> For many years (off and on - not continuously) I have taught introductory
> physics and I do it without using the term "weight" at all.  (Or only in
> telling the students to ignore the term in their textbook, and use
> mg/gravitational force instead.)  All my free-body diagrams include a
> gravitational force mg (g being due to everything in the universe), and
> that's what I call it.  No W vector, so W is only work.  When we discuss
> moving and/or accelerating elevators, we may talk about the upward normal
> force of the elevator floor on a person, but I don't call that "apparent
> weight" either.
>
> I can then ask the question, what is meant in ordinary English by the
> feeling of "weightlessness" in a spaceship orbiting the earth?  No
> gravitational force?  No!  No normal force pushing on you?  Yes.
>
> In mechanics we find it useful to clearly define "velocity" and "speed" in
> the physics sense, which may not coincide with the ordinary English uses of
> these terms.  But I see no purpose in using the term "weight."  It
> unnecessarily confuses students.
>
> Colleagues who teach with me in the same course accept this easily, but
> most of my colleagues use "weight" when teaching introductory physics.
>
> Can't we get rid of the term?
>
> Laurent Hodges, Professor of Physics
> 12 Physics Hall, Iowa State University, Ames, IA  50011-3160
> lhodges@iastate.edu   http://www.public.iastate.edu/~lhodges