Re: A weighty matter

[Larry Cartwright <exit60@IA4U.NET>]

Marc Kossover wrote on Friday, October 15, 1999 2:48 PM :
> > From the PSAT given on Tuesday:
>
> 6. METER : DISTANCE ::
>
> (a) ounce : pound
> (b) gram : weight
> (c) container : liquid
> (d) size : height
> (e) boundary : periphery

If this question was intended to test knowledge of which units measure
which quantities in standard physics usage, it obviously falls short.

However, as a test of the person's ability to make logical connections
beyond the standard usages which may have been memorized (e.g. "grams :
mass", and "Newtons : force", and "pounds : weight", etc) the question
is actually pretty good.

"Meter" is a unit, "distance" is a quantity; "gram" is a unit, "weight"
is a quantity.  Relationship established, case closed.

And from a logical point of view, the fact that "meter" is the unit used
to measure "distance" does not *compel* that "gram" be the unit used to
measure "weight".  Any unit:quantity pair will suffice, even if
dimensionally mismatched.

"METER : DISTANCE :: Watt : Time" is a perfectly valid *logical*
relationship.

I kinda like questions like that.  It gives one a bit of a start when
the expected "right answer" isn't there; and then one has to start
thinking about the validity of the choices that have been offered.

If there's anything really wrong with the PSAT question, it's that it
makes people with more technically precise knowledge (i.e. "physics
wonks") think harder than average folks.  But of course we are all
painfully acquainted with the fact that the more you know, the more
complex everything seems and the harder is is to arrive at what's
"right".

\\//,

Larry

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Larry Cartwright  <exit60@ia4u.net>
Physics and Physical Science Teacher, Charlotte HS, MI, USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~