Re: Problem with a problem

[Leigh Palmer <palmer@SFU.CA>]

> Could you elaborate a little on what makes this problem "poorly specified"?
> I have re-read it several time and still don't see it (unless it's that the
> acceleration vector is not specified to be in the plane of rotation).

I see ambiguity in the specification of the angle. I see four
possible orientations for the acceleration, each of which
"makes a 60.0 degree angle with respect to the rod" and lies
in the plane of interest. I also would not specify "60.0"
degrees if I meant *exactly* sixty degrees. I would simply
specify 60 degrees. That may be a matter of taste; the
ambiguity in the angle is not. Most physics teachers will
choose one of these by lazy experience; an inexperienced
student may not. We have to learn to look at these problems
from their viewpoint.

> Though "intrinsically interesting" problems are probably best, I find that
> some students (particularly the "better" ones) appreciate any problem that
> helps them solidify their understanding of some concept, even if the problem
> was obviously contrived solely for that purpose.

The problem of the irreversible compression really helped me
to do that. The pencil problem (q.v.) shows that something
can be dropped and move faster than a freely falling body
dropped from the same height. That should help. The problem
presently under consideration doesn't solidify any concept
for me, and I think it is unlikely to do so for a student.
The impression that physics is about dull things does come
through loud and clear, however.

(It should go without saying, but of course I recognize I'm
only expressing my opinion. Whose do you expect from me?)

Leigh