Re: [Phys-l] force conventions

["Krishna Chowdary" <professor.head@gmail.com>]

On 10/27/06, John Denker <jsd@av8n.com> wrote:
> We can define
>   Fu = force exerted *upon* a body by the surroundings
>   Fb = force exerted *by* a body upon the surroundings.
>
> It is /conventional/ to write N2 in the form
>   Fu = m a                 [2]
>
> Non-experts would be well advised to stick with this conventional
> formulation ... but we should keep in mind that this is little
> more than a convention, because it would be utterly straightforward
> to reformulate the laws in terms of Fb.
>
> Fu = -Fb in accordance with N3.
>
> Fb is not one iota less "real" than Fu.  It's just less suitable
> for use in equation [2].

(I have found this discussion and its branches very interesting, and thank
John Denker for starting it.)

Just yesterday I read this paper:

http://www.physics.umd.edu/perg/papers/scherr/NZeroPre.pdf

and find John D.'s comments to be quite compatible with what this paper
calls "Melaneian mechanics", and especially the overlapping comments about
students' alternative conceptions.


--
regards
-Krishna

Krishna Chowdary
Department of Physics & Astronomy
Bucknell University