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Re: F=m*a before kinematics?



THIS IS THE WAY IT SHOULD BE DONE!

We used to do this at Lehigh, when we used the book by Radin & Folk. It
workd excellently! We taught vectors with F=ma, and the students
immediately saw the reason for vectors! And, then they see the need for
the kinematics equations and how the acceleration applies!

We had TREMENDOUS success doing it this way! If I could find a book to
o it this way now, I'd jump at it! I think many others would as well,
witness a commentary article in the AJP about this several years ago!

Alas, the "book people" seem entrenched in only one way of doing it --
the worse way of the two I've seen.

If anyone has seen a decent text doing it this way, please let me know.

Peter Schoch


Ludwik Kowalski wrote:

... Fortunately the sign rules [deceleration does not
always mean negative a] become less confusing after
the F=m*a formula is digested by students.

It occurred to me that, perhaps, it would be better to teach
dynamics before spending too much time on problems
of kinematics. The basic concepts (t, s, v and a), and
the corresponding units, would be quickly covered in
the introductory chapter. Next students would learn
F=m*a (net force is needed to produce acceleration).
Only then would they focus on problems of formal
kinematics. Separation of kinematics from dynamics
may be responsible for some unnecessary difficulties.

Did somebody try this? How did it go?
Ludwik Kowalski