Re: Newton's 3rd law? was Re: inertial forces (definition)

[Leigh Palmer <palmer@SFU.CA>]

> The problem with students, as I see it, is that they interpret
> "centripetal force" as being one of those four fundamental forces of
> nature, separate from the gravitational, electrical and nuclear forces.

This is a problem that is exacerbated in the textbook I'm using,
Hecht's "Algebra/Trig" version. Chapter 5 is titled "Centripetal
Force and Gravity"!

> The same is true for the centrifugal force.  In my class, I prefer that
> students use "force directed toward the center" and "force directed away
> from the center" for centripetal force and centrifugal force.  Then, when
> I ask which force is directed toward the center of the motion, I am less
> likely to get the "force directed toward the center" as the answer.

That is the solution I would like to use. How do you protect
your students from the bad influence of textbooks? The market
demands that "centripetal force" be included in all textbooks.
Tradition does not serve us well in this regard either.

Leigh