Re: plug and chug

[John Mallinckrodt <ajm@CSUPOMONA.EDU>]

> Hi John-
> IMO both John Clement's and this amusing problem have too much detail, so
> that the real point of the problem may easily get lost in the p&c aspects.

I understand and agree.  Since p&c problems occupy a very specific
and narrow range on the spectrum, "non p&c" only tells us what the
problem *isn't.*  What we are really talking about are problems that
are *very* simple, but that will not yield to the mindless
application of formulas.

> If you get hung up on whether the "friend" pushes the skier "forward" or
> pushes "on the skier's back", where the real issue is whether the push
> force is hard enough to overcome static friction, ...

I still don't consider my objection to be "getting hung up."  The
first issue in the skier problem *has* to be whether or not the skier
is moving and which way.  There are at least three different answers
to this problem depending on that piece of information.  Only after
one has established that the skier is at rest is the real issue
whether or not the push is hard enough to overcome static friction.

I know that you mean for the students to understand that the skier is
at rest, but I think you are sending them needlessly contradictory
messages.  Why use the phrase "pushed forward" if the skier is at
rest?  Why not simply eliminate the ambiguity by using the wording I
suggested?  Do you *really* not agree that a student could read your
problem and decide that the skier is moving?

--
John Mallinckrodt        mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm