I don't disagree with John's listing of four distinct ideas. Indeed, I
find his description helpful.
But whether right or not, I still maintain that when I write Newton's
2nd Law as a = F/m I can see students having an "Aha!" moment. They
have always encountered it as F = ma, and they were thinking causality,
and it didn't click for them. Why should mass times acceleration create
a force? I don't think there is any doubt many students have been
confused about F = ma. They have told me so.
Again please note I am not saying I disagree with John that = does not
and should imply causality. Rather, I am stating what my incomming
students think, and I am always trying to find ways to get through to
them. I have found if I always write N2L as a = F/m, it helps the
students.
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu