Lateral < Thinking

This one is a true incident. It goes as follows...
"Some time ago I received a call from a colleague. He was
about to give a student a zero for his answer to a physics
question, while the student claimed a perfect score.
The instructor and the student agreed to an impartial arbiter,
and I was selected. I 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 it 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."

The student really had a strong case for full credit since he
had really answered the question completely and correctly!
On the other hand, if full credit weregiven, it could well contribute
to a high grade in his physics course and to certify competence
in physics, but the answer did not confirm this.

I suggested that the student have another try. I gave the student
six minutes to answer the question with the warning that
the 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 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
x=0.5*a*t^2, calculate the height of the building."

At this point, I asked my colleague if he would give up. He
conceded, and gave the student almost full credit. While
leaving my colleague's office, I recalled that the student had
said that he had many answers to the problem, so I asked him
what they were.

"Well," 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 simple proportion, determines the
height of the building."

"Fine," I said, "and others?” Yes," said the student, "there
is a very basic measurement method 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, in principle,
can be calculated."

"On this same tact, you could take the barometer to the top of
the building, attach a long rope to it, lower it to just above the street,
and then swing it as a pendulum. You could then calculate the height
of the building by the period of the precession". 

"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 is a fine barometer. If you will tell me the
height of the 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."

The student was Neils Bohr and the arbiter was Rutherford.