Re: speed and velocity

[Brian McInnes <bmcinnes@PNC.COM.AU>]

> Date: Tue, 1 Dec 1998 4:02 AM
> From: Phil Parker <PPARKER@TWSUVM.UC.TWSU.EDU>


> In mathematics we distinguish between scalar components and vector
> components for precisely this reason.  We would say Bob
mentioned vector
> components, and you've described scalar components.
>   Also in mathematics, vectors can have signs, but the
sign attached to a
> vector is conceptually different from the sign attached to
a number. Using
> the same minus symbol for both is a bad idea from a purely
conceptual view,
> but it's very human.

Phil,
 Let's see if I understand you.
(1) By "vector components" do you you mean scalar components
of a vector multiplied by a unit vector along the
appropriate axis?
(2) Why do you want (or need) signs for vectors?

Surely a particular vector has a direction and another
vector has a different direction.  I guess an exception to
this is the rather sterile case where all the vectors lie
along a particular line. In general, the vectors, whether
they are forces or fields or velocities or whatnot, will lie
in different directions.  Combinations of them can be done
geometrically or by taking components and using unit vectors
(explicitly or implicitly).

In replying to Bob Sciamanda you say "It is important to
keep the distinction between numbers as numbers (scalars)
and numbers as 1-dimensional vectors.  This post thoroughly
confuses the two senses."  What I find confusing is the idea
that numbers, which are pure magnitude (surely) can be
vectors (1-dimensional or otherwise)!

Brian McInnes