Re: force

["Roger A. Pruitt" <phrp@fhsuvm.fhsu.edu>]

Joseph Bellina wrote:
> On Thu, 31 Oct 1996, Roger A. Pruitt wrote:
> > To a physicist, both acceleration and force are real observable
> > quantities, however, I think that of the two that acceleration is the
> > more abstract.
>
> I would suggest that force is experienced, but not observed, whereas
> acceleration is observed, but not experienced...and therein lies part of
> the problem.  Force is a real ghost in the machine for physics...when
> push comes to shore (heh..heh), we really know what it is.
> Roger, what do you think it is?
>
> cheers
>
> Joe

Joe, I agree in general with everything you said. However, I often think
that we nitpic too much on this list. I include myself as I have risen
to the bait and commented on current flow, heat, g, and now force and
acceleration. Gene Mosca noted that we observe deformations--not forces.
At one level this is certainly correct. A sensor has to deform in order
to produce a signal that will indicate a force. Even when I push on the
desk with my hand, I am producing a deformation in the nerve cells in my
hand that indicate that I am applying a force. At this level, you are
also correct to say that we experience the force--not observe it. I was
using the more general expression, universal in physics, that we observe
it, and not meaning by "observe" that we see it.

In this sense we observe both accelerations and forces. However, I still
maintain that forces are easier to observe, and even the qualitative
"measurement" (estimate) of a force is more direct that making a
qualitative "measurement" of an acceleration. The later involves too
many indirect steps and mental computations as I pointed out in a
previous comment.

Incidently, Roger Haar has taken some criticism from others for comments
made by me. Roger, please accept my appology, and I hope that other
readers went back and reread the header and realized that you are not to
be blamed for my ideas.

Roger Pruitt