Re: Nomenclature: Normal forces

[Tim O'Donnell <odonnt@CELINA.K12.OH.US>]

> As a final observation, I wonder how many of our students
> think that "normal" force means the "usual" or "ordinary"
> force.
>
> Brian McInnes

This is why I emphasize that "normal" is a mathematical term
meaning perpendicular.  Is is old language, but I'm old enough
I guess.

From Merrian Webster's Collegiate Dictionary
Main Entry: 1nor·mal {HYPERLINK "javascript:popWin('/cgi-bin/audio.pl?normal01.wav=normal')"}{HYPERLINK "javascript:popWin('/cgi-bin/audio.pl?normal01.wav=normal')"}
Pronunciation: 'nor-m&l
Function: adjective
Etymology: Latin normalis, from norma
Date: circa 1696
1 : {HYPERLINK "dictionary?book=Dictionary&va=perpendicular"}PERPENDICULAR; especially : perpendicular to a tangent at a point of tangency
2 a : according with, constituting, or not deviating from a norm, rule, or principle b :
conforming to a type, standard, or regular pattern
3 : occurring naturally <normal immunity>
4 a : of, relating to, or characterized by average intelligence or development b : free
from mental disorder : {HYPERLINK "dictionary?book=Dictionary&va=sane"}SANE
5 a of a solution : having a concentration of one gram equivalent of solute per liter
b : containing neither basic hydroxyl nor acid hydrogen <normal silver phosphate>
c : not associated <normal molecules> d : having a straight-chain structure
<normal pentane> <normal butyl alcohol>
6 of a subgroup : having the property that every coset produced by operating on
the left by a given element is equal to the coset produced by operating on the right
by the same element
7 : relating to, involving, or being a normal curve or normal distribution <normal
approximation to the binomial distribution>
8 of a matrix : having the property of commutativity under multiplication by the
transpose of the matrix each of whose elements is a conjugate complex number with
respect to the corresponding element of the given matrix