[Phys-L] Re: notation for initial velocity components
From: edmiston at BLUFFTON.EDU (Edmiston, Mike)
Date: Fri Oct 21 12:10:30 2005
Well... yeah... That's the problem. There are some logical reasons for
choosing each notation. And, I have seen books switch midstream,
although I don't remember which books do that. The switch seems to come
about because they are following Joel's advice in the mechanics section
under Newton's Laws, and they are following Carl's advice in the
electrostatic section for superposition. That is, the net force on
charge-1 because of other charges present is F(1net) = F(12) + F(13) +
F(14) etc.
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu
Carl...
| I agree with Michael's notation and the reason I like F_12 is because
| I think of the 2nd subscript as a semi-optional
| sub-subscript: hence
| F_1 = sum over i of F_1_i. (Optional because if there are only two
| objects of interest then the net force on 1, F_1, is the force on 1
| due to 2, F_1_2. The subscript 2 is then only a reminder, which we can
| drop when we get tired of writing it.) -Carl
| --
Joel...
OTOH, the subscript, particularly in a FBD, usually refers to the object
causing the force, not the object receiving the force.
E.g. F_s for spring force acting on an object, or F_T for the tension
in a rope acting on an object, etc.