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Re: operational F, m, and a (velocity measurements with fish-scal es)



At 11:32 AM 10/19/01 -0500, RAUBER, JOEL wrote:
If you are operating it in an equilibrium manner, have you not made a
velocity measurement of the pointer relative to the tick-mark scale?

Whether or not I have made a velocity measurement is irrelevant. The
position matters; the velocity does not. To keep me honest, let my lab
technician make the measurement. He then emails me the x reading but not
the (dx/dt) reading. I still know the force.

This is a PHYSICS experiment that tells me that the pointer-position
matters and the velocity does not (to an excellent approximation for any
halfway-decent spring-scale).

Any observation of the velocity is an irrelevant accident, a red herring, a
distraction.

The experimental evidence is the evidence of how everyone I have ever
chatted with uses a spring scale.

This is not physics. This is some form of sociology, and not very
systematic sociology.

Everyone _I_ have chatted with recognizes the parallels between the spring
scale and the mass-on-a-spring oscillator. They have no trouble writing
down the equation of motion that involves a force dependent on the POSITION
(i.e extension) of the spring, independent of the velocity, even when the
mass is oscillating, i.e. far from equilibrium.

Physics does not restrict springs to producing forces only in
equilibrium. Any such restriction exists in the imagination of those who
wish to imagine it.