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-----Original Message-----***********
From: Carl E. Mungan [mailto:mungan@USNA.EDU]
Sent: Wednesday, October 17, 2001 1:27 PM
To: PHYS-L@lists.nau.edu
Subject: Re: operational F, m, and a
Joel wrote:
I still think there is an implicit acceleration measurement occuring,which I will
however. Remember we are dealing with Newton's second law,
paraphrase as:acting on an object
In an inertial frame of reference, the sum of the forces
is equal to the objects mass times its acceleration.force in the context
That means, in order to use the fish scale to determine
of Newton's second law I have to make sure that the tickmark scale on the
apparatus is a good inertial frame of reference, which means I mustthe tick mark
implicitly make another kinematic measurement, namely that
scale has zero acceleration relative to some fiducialinertial frame of
reference.determinations of
If you buy this, it means that equilibrium measurement
force involve measurement of acceleration.
Can't we use Newton's first law (N1) to decide if a reference frame
is inertial?
Specifically, find an object which is isolated (ie, in deep space -***********************************
this is a Gedanken experiment). Now look to see whether the object is
accelerating relative to your reference frame.
*******************
Thus, I take N1 to be a definition (namely of an inertial frame).
With this definition, I now take N2 as an experimental law, in accord
with John D's prescription.
--
Carl E. Mungan, Asst. Prof. of Physics 410-293-6680 (O) -3729 (F)
U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mungan@usna.edu http://physics.usna.edu/physics/faculty/mungan/