Although I'm still confused about John Mallinckrodt's mass and power
vectors, I think I just realized another thing he was saying about my
view of unit vectors which means I was viewing it incorrectly.
What helped me see this was thinking about unit-vector-r between two
objects such as charges that are attracting or repelling. We calculate
unit-vector-r by dividing vector-r by the magnitude of vector-r. Let's
suppose I had two objects in space and vector-r runs from
center-of-object one to center-of-object-two. Let's suppose in my
scale of things the magnitude of vector-r is 6 meters. I would have
been inclined to draw unit-vector-r starting on object-one and
extending one-sixth the distance to object two.
John is saying I would not have needed to draw it that way. I could
have drawn unit-vector-r one half the distance, one-fourth the
distance, or even 10 times the distance. I now admit that John is
correct, and I admit that I have, for many years, drawn unit-vector-r
as extending one-sixth the way across.
Misery likes company. Please tell me that there are many others of you
who would have drawn it the same as I.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817