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Re: Apparent weight



On Thu, 26 Feb 1998, David Dockstader wrote:

But these are only sensitive to differential stress. You have no absolute
scale.
On Wed, 25 Feb 1998 15:42:07 -0600 (CST) A. R. Marlow said:

I don't have a problem with the naive way as a rough initial indicator for
the primitive concept of force: for the human tactile sensor, the
atmospheric pressure equilibrium situation is taken as the normal (zero
net force), and felt departures from this of greater or lesser
"amount" (from light to forceful all the way to painful) are taken as
rough measures of greater or lesser forces being applied. Granted the
subjective nature of such sensitivity, much refinement is needed (as in
all cases of going beyond the estimation of the human senses to real
scientifically precise measurement), but its a start. Piezoelectric
sensors would be a possible next step, with zero potential difference as
the zero reading.

A. R. Marlow E-MAIL: marlow@loyno.edu
Department of Physics, Box 124 PHONE: (504) 865 3647 (Office)
Loyola University 865 2245 (Home)
New Orleans, LA 70118 FAX: (504) 865 2453



Is that a problem? Just about any physical quantity seems to be able to
be construed that way. As soon as you think you have an absolute zero for
electric charge, Dirac comes along and tells you that you are actually
measuring relative to an infinite background of negative charge as your
"zero" point. Does that make charge, or force, any less real? Once you
have fixed a zero, even if arbitrary, then you can compare the
(differential) effects of real forces to fictions to see if they are
the same or not. You find out that fictions lack third law counterparts,
among other things, and are not experienced except as kinetic
effects (accelerations) relative to noninertial frames of reference.


A. R. Marlow E-MAIL: marlow@loyno.edu
Department of Physics, Box 124 PHONE: (504) 865 3647 (Office)
Loyola University 865 2245 (Home)
New Orleans, LA 70118 FAX: (504) 865 2453