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... . The acid test, then, for a
*real* force is "Does it cause deviation from local inertial motion?" If
it does it is a force; if it doesn't it is not a force. And this holds in
both Newtonian and Einsteinian physics.
Given your defining acid test above for a force everything you have been
saying seems to be consistent. I just don't choose to use this criterion
to define what I mean by a force. According to your definition of force
frame generated influences on the motion of a body in a given reference
frame cannot be called forces, and hence you call them fictious. Only
interaction-generated forces pass your (very low pH) acid test. My, much
weaker, test for a force is that if, in a given frame, it mathematically
functions as a force as far as its role in the equations of motion and in
its relationship to various integrals of the motion (action, Lagrangian,
Hamiltonian, etc.), then it is a force regardless the mechanism of its
ultimate generation (physical interaction or frame acceleration). I prefer
the duck test to an acid test.
David Bowman
dbowman@gtc.georgetown.ky.us
Well then, according to your weaker criterion, forces become
accelerations; why use the two distinct terms? Why teach our students
two distinct terms if they really always mean the same thing? How
would you distinguish the two terms pedagogically? I am really asking
this to gain enlightenment on how to teach these matters in a practical
way.
A. R. Marlow E-MAIL: marlow@loyno.edu
Department of Physics, Box 124 PHONE: (504) 865 3647 (Office)
Loyola University 865 2245 (Home)
New Orleans, LA 70118 FAX: (504) 865 2453