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Re: [Phys-l] scope of the course



John!


On 2012, Feb 05, , at 10:13, John Denker wrote:

On 02/05/2012 01:08 AM, Bernard Cleyet wrote:
p.s. Since this is an intro prob. i.e. algebra only, no calculus,
one must assume the friction is constant.

I disagree, for at least three reasons.

*) The law for radioactive decay says the rate-of-change of x is
proportional to x. This is generally considered well within the
scope of the algebra-based physics course. Viscous damping follows
the same law. Eddy-current damping follows the same law.


I'm too lazy to see how, w/ algebra, one may derive the exponential relationship, please "show me".


*) The case where the resistance is dependent on /position/ not
velocity -- including the scenario where the block hits a peg --
is well within the scope of the algebra-based physics course.


OK, at least w/ the peg scenario.


*) The original question came from a /college/ course. At the
college level, not all first-year courses eschew calculus.


OK, I goofed. AFAIK, no HS has .edu addresses.

Moreover, I'm stuck in my experience of going to a (then) second rate college (later a UC campus). Our first course was algebra, not calc., a repeat of my HS course.


======================

More importantly: When solving real-world problems, it is
essentially always necessary to make assumptions. Unless
you are quite sure everybody knows what assumptions are
being made, it pays to
1) At least document what assumptions you are making.
2) Preferably, check to see whether the conclusions are
unduly sensitive to the assumptions.


OTOH, as I think you've writ, it affords teaching moments, wherein the students do as you've suggested, i.e. "do" the prob. w/ various assumptions.


To say the same thing another way: If you've been warned that
people have been having trouble with a seemingly "simple"
problem, you could
A) Assume they are all stupid, or

bc in this group?


B) Consider the possibility that the problem is ill-posed,
and that different people are making different assumptions.
Different is not necessarily wrong.


As long as included in the work is a statement of the assumptions.


bc thinks he's learned a little from this prob.


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