Re: momentum before force

["Daniel L. MacIsaac" <danmac@physics.purdue.edu>]

> Paul: as you say, the idea of momentum has an ancient history in which is
> co-evolved with the idea of force.  I'm looking for a way to short-circuit
> that evolution by motivating momentum *without* the idea of force ---
> purely so that only one new concept needs to be introduced at a time.
>
> --James McLean

In the history of mechanics, Oresme and Buridan developed the idea of momentum
as the natural "quantity of motion" -- a quantity proportional to how much 
stuff is moving and how fast it moves.  Nicole Oresme worked around 1350 
(250 years before Galileo, who also worked on the same idea before Newton). 
Jean Buridan (50 years before as rector of the university of Paris) developed
the roots of Oresme's work on what was then called IMPETUS.  Galileo and Newton
followed both.

Newton worked in dP/dt -- the change in momentum (he was too cagey to 
assume constant mass like the statement F = ma is often misinterpreted).
> From IMPETUS or the better-differentiated MOMENTUM that followed, he 
defined force.

There are web entries on all these people through the DEC ALTA VISTA engine,
and both _The Mechanical Universe_ and Piaget & Garcia's _Psychogenesis and the
History of Science_ discuss this.  Alternatively, one could take EDCI 695
here at Purdue and learn about these ideas and many other pertainent insights
into how human beings learn and do physics as part of a graduate degree 
in science education.  We have a number of graduate physics students doing
so voluntarily and finding the experience to be worthwhile.

Dan M

Dan MacIsaac, Assistant Professor of Physics and Astronomy, Northern AZ Univ
Visiting Asst Prof, Purdue Univ Physics;  Adjunct Faculty, Indiana U at Kokomo
NEW NET ADDRESSES:  danmac@nau.edu  http://www.phy.nau.edu/~danmac
Ph.D. in Education: Curriculum & Instruction