From: bwillan4@mach1.wlu.ca (brian willan 9209 U)
Subject: Re: physics jokes
Date: Fri, 5 Mar 1993 14:22:27 GMT

                Angels on a Pin
 
  Some time ago, I received a call from a colleague who asked if I would
be the referee on the grading of an examination question.  He was about
to give a student a zero for his answer to a physics question, while the
student claimed he should receive a perfect score and would if the
system were not set up against the student.  The instructor and the
student agreed to submit this to an impartial arbiter, and I was
selected.
 
  I went to my colleague's office and read the examination question:
"Show how it is possible to determine the height of a tall building with
the aid of a barometer."
 
  The student had answered: "Take the barometer to the top of the
building, attach a long rope to it, lower the barometer to the street,
and then bring it up, measuring the length of the rope.  The length of
the rope is the height of the building."
 
  I pointed out that the student really had a strong case for full
credit, since he had answered the question completely and correctly.  On
the other hand, if full credit were given, it could well contribute to a
high grade for the student in his physics course.  A high grade is
supposed to certify competence in physics, but the answer did not
confirm this.  I suggested that the student have another try at
answering the question.  I was not surprised that my colleague agreed,
but I was surprised that the student did.
 
  I gave the student six minutes to answer the question, with the
warning that his answer should show some knowledge of physics.  At the
end of five minutes, he had not written anything.  I asked if he wished
to give up, but he said no.  He had many answers to this problem; he was
just thinking of the best one.  I excused myself for interrupting him,
and asked him to please go on.  In the next minute, he dashed off his
answer which read:
 
  "Take the barometer to the top of the building and lean over the edge
of the roof.  Drop the barometer, timing its fall with a stopwatch.
Then, using the formula S=*+at}, calculate the height of the building."
 
  At this point, I asked my colleague if _he_ would give up.  He
conceded, and I gave the student almost full credit.
 
  In leaving my colleague's office, I recalled that the student had said
he had other answers to the problem, so I asked him what they were. "Oh,
yes," said the student.  "There are many ways of getting the height of a
tall building with the aid of a barometer.  For example, you could take
the barometer out on a sunny day and measure the height of the
barometer, the length of its shadow, and the length of the shadow of the
building, and by the use of a simple proportion, determine the height of
the building.
 
  "Fine," I said.  "And the others?"
 
  "Yes," said the student.  "There is a very basic measurement method
that you will like.  In this method, you take the barometer and begin to
walk up the stairs.  As you climb the stairs, you mark off the length of
the barometer along the wall.  You then count the number of marks, and
this will give you the height of the building in barometer units.  A
very direct method.
 
  "Of course, if you want a more sophisticated method, you can tie the
barometer to the end of a string, swing it as a pendulum, and determine
the value of 'g' at the street level and at the top of the building.
From the difference between the two values of 'g,' the height of the
building can, in principle, be calculated."
 
  Finally he concluded, there are many other ways of solving the
problem.  "Probably the best," he said, "is to take the barometer to the
basement and knock on the superintendent's door.  When the
superintendent answers, you speak to him as follows: 'Mr.
Superintendent, here I have a fine barometer.  If you will tell me the
height of this building, I will give you this barometer.'"
 
  At this point, I asked the student if he really did not know the
conventional answer to this question.  He admitted that he did, but said
that he was fed up with high school and college instructors trying to
teach him how to think, to use the "scientific method," and to explore
the deep inner logic of the subject in a pedantic way, as is often done
in the new mathematics, rather than teaching him the structure of the
subject.  With this in mind, he decided to revive scholasticism as an
academic lark to challenge the Sputnik-panicked classrooms of America.


***


Jeff Kawski writes:
> My friend once saw a question like this on his physics final:
>
> A physics student is asked to find 3 ways to use a barometer to determine
> the height of a tall building.  His replies are as follows:
>
> 1.  Find someone who knows how tall the building is, and trade him the
>     barometer for the information.

Jeff Roberts replies:
>   Wasn't this joke ripped off from the first episode of "Head of the Class"
> (bunch'a brainy kids led by real-world substitute)?

   No way; this joke dates back to at least 1951. Sharvey Umbeck, president of
Knox College, told this one at every convocation for his 24 years at the helm of
my dear alma mudhole. I would be surprised if he invented it: he told it as if
it were much older. He used it to underscore the breadth of the liberal arts.
The canonical reply list was:

0. What the teacher wanted:
   Measure the barometric pressure at the top and bottom of the building.
   Plug these into the equation in the book and spit out the answer.
1. Student's first attempt:
   Trade the barometer to the building's owner for the height.
<teacher rejects: no property characteristic of the barometer>
2. Measure the height of the barometer. Scale the side of the building,
   measuring its height in barometer-units.
<rejected: uses no basic scienctific principles>
3. Drop the barometer from the top of the building. Measure the time until it
   hits the street. Correcting for the mass/surface ratio of the instrument,
   use basic acceleration equation to find the height.
<rejected: barometer is no longer a barometer>
4. Tie string to top of barometer. Lower from roof to almost ground. Swing.
   Period of pendulum can be used to find distance from barometer's CG to top
   of building. Add displacement from CG to bottom of barometer; this is height.
<rejected: does not incorporate barometer's intended function>
5. Oh! You want that *boring* stuff from the beginning of the term! What is
   something this simple doing on the final? Anyone who doesn't know that has
   already dropped. I assumed you wanted us to *think*!


***