Re: [Phys-l] g...

["Josh Gates-fac" <Josh_Gates-fac@nobles.edu>]

I agree that using subscript notation (v for all vs, a for all as, etc.)
is, in principle, more simple and therefore should be more easily
comprehended, BUT...
my students have tremendous difficulty differentiating between
"subscripted" quantities - to many of them, a v is a v, is a v, etc.  So,
I use N for normal, T for tension, etc.   For vs and xs and Es, etc. I
still use subscripts, but the prevalence of mistaken identity in variables
is much higher than it is with the forces.

This seems to be a symptom of what I call "caveat blindness," which goes
something like this:
Every time I say "x only when y," "x, provided y is true," or "if y, then
x," all most of them hear, or at least commit to memory, is "x."  There's
a sect that wants Fnet = 0 always, a group that wants delta p = 0 always,
a gaggle of delta KE = 0 always believers, a herd that wants us*N = static
friction force always, etc.  I haven't identified a presentation method,
syntax, or activity to get the "caveats" ingrained as firmly as the
"results."  This holds true even if they can speak, _in their own words_ 
a correct version of, say N's 1st - the connection isn't always made
between that kind of understanding and a physical situation to be analyzed.

Any suggestions welcome!

Josh Gates
Stoneleigh-Burnham School
Greenfield MA

> trained professor.  Tougher in his book does sometimes use F for different
> forces such as F_grav, F_normal, but then he illogically departs by using
> T
> for tension as if it is a different type of force.  Knight adheres to
> tradition, which I think is a grave mistake.  By not using a for all
> accelerations, and F for all forces coherence has been decreased.
>
> John M. Clement
> Houston, TX