I appreciate John Denker's comment about the need for cleanliness and
simplicity in intro. physics problems, and I've learned quite a bit
about drag, lift and thrust recently, for which I thank everyone
involved. Still, we intro teachers need to balance the need for rigor
and careful, complete definitions on the one hand with the need to
include problem settings that use the language of the world outside our
classroom. The real-world connection is what draws a great many of our
students into the discussion in the first place. It does also bring in
messiness and approximations.
I know (especially now!) that I cannot discuss thrust and drag with the
precision of an aeronautical engineer. Still, I do tell my students
often that many of our discussions involve approximations that will be
removed in higher level physics and engineering courses. So, I like the
airplane problem that provoked the discussion and intend to use
something along those lines next year. Incidentally, John's point about
the multiple demands of test questions is well-taken. I think students
should be offered ample practice before exams on the sort of test items
included on the exam. Assigning text problems and then giving
multiple-choice tests changes, IMHO, the focus from physics to
test-taking skills.
I hope my students will be open-minded enough in their advanced courses
to tolerate more precise definitions and that their professors will
accept the need to rigorously define their terms. At least I am sending
along students who, by and large, have a Newtonian, rather than an
Aristotelian world-view ( according to FCI and other assessments) , and
also sufficient interest to actually enroll in those more advanced
courses. How cool is that!!