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Re: operational F, m, and a



At 12:39 PM 10/16/01 -0500, RAUBER, JOEL wrote:

To say it in more positive terms: We have an
operational definition of force.

Agreed.

And here is the operation. Measure a, something we can do without reference
to F=ma (see kinematics chapters of most introductory texts); measure m,
something we can do without reference to F=ma (see Eisenbud, Am. J. Phys.,
26,144,(1958); or Mach, "Science of Mechanics", Open Court, NY,1942).

then use F=ma to calculate F.

That's not what I'd recommend. Consider a rather more direct operational
definition: Take a spring scale, like they sell at the fishing store.
When the spring is extended a certain amount, it indicates a certain force.
Two fish scales give a resultant force according to a vector sum law.
Blah blah et cetera et cetera.

We have an operational definition of
mass.

We do?

Take a chunk of stuff. Two chunks stuck together have a larger mass
according to a scalar sum law. Blah blah you get the idea.

We have
an operational definition of acceleration.


We do?

(d/dt)(dx/dt). Vector. Blah Blah.......