Re: tautology

Brian D Harper (harper.10@osu.edu)
Fri, 27 Jun 1997 16:40:12 -0400

At 03:08 PM 6/27/97 -0400, I wrote:
[...]
>
>I've never actually read through the Principia. Glancing through
>the first few pages just now I notice that Newton introduced a
>number of things by way of definitions. For example, mass, momentum
>and acceleration are all defined quantities. The second law was
>stated differently, as a law or axiom rather than as a definition
>of force. For the moment anyway, I have to believe that Newton
>had a reason for doing this and that he did not consider his
>second law as merely a definition of force.
>

sorry to followup on my own post. Looking through <A History of
Mechanics> by Rene Dugas I found the following:

"In this way Newton multiplied the definitions and concepts.
Instead of deducing the concept of motive force from the
concepts of mass and acceleration by using the law (1),
he consciously regarded the mass and the force as two
primarily distinct notions" -- Dugas p. 203, Dover ed.

Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University

Feynman's Second Law:
"everything stands still except when a gorce is acting"