Sorry, Dien. Can't help it. For your "How to be creative" file...

This legend, the truth of which is not necessarily related to its value,
concerns a question in a physics degree exam at the University of
Copenhagen: "Describe how to determine the height of a skyscraper with a
barometer."

One student replied: "Tie a long piece of string to the neck of the
barometer, then lower the barometer from the roof of the skyscraper to
the ground. The length of the string plus the length of the barometer will
equal the height of the building."

This highly original answer so incensed the examiner that the student was
failed immediately.

He appealed on the grounds that his answer was indisputably correct, and
the university appointed an independent arbiter to decide the case. The
arbiter judged that the answer was indeed correct, but did not display any
noticeable knowledge of physics.

To resolve the problem it was decided to call the student in and allow him
six minutes in which to provide a verbal answer which showed at least a
minimal familiarity with the basic principles of physics.

For five minutes the student sat in silence, forehead creased in thought.
The arbiter reminded him that time was running out, to which the student
replied that he had several extremely relevant answers, but couldn't make
up his mind which to use.

On being advised to hurry up the student replied as follows:

"Firstly, you could take the barometer up to the roof of the skyscraper,
drop it over the edge, and measure the time it takes to reach the ground.
The height of the building can then be worked out from the formula H =
0.5g x t squared. But bad luck on the barometer.

"Or if the sun is shining you could measure the height of the barometer,
then set it on end and measure the length of its shadow. Then you
measure the length of the skyscraper's shadow, and thereafter it is simple
matter of proportional arithmetic to work out the height of the
skyscraper.

"But if you wanted to be highly scientific about it, you could tie a short
piece of string to the barometer and swing it like a pendulum, first at
ground level and then on the roof of the skyscraper. The height is worked
out by the difference in the gravitational restoring force T = 2 pi sq root(l
/ g).

"Or if the skyscraper has an outside emergency staircase, it would be
easier to walk up it and mark off the height of the skyscraper in barometer
lengths, then add them up.

"If you merely wanted to be boring and orthodox about it, of course, you
could use the barometer to measure the air pressure on the roof of the
skyscraper and on the ground, and convert the difference in millibars into
feet to give the height of the building.

"But since we are constantly being exhorted to exercise independence of
mind and apply scientific methods, undoubtedly the best way would be to
knock on the janitor's door and say to him 'If you would like a nice new
barometer, I will give you this one if you tell me the height of this
building'."

The student was Niels Bohr, the only Dane to win the Nobel Prize for
Physics.

Hi Simon!

That was a great post.... It shows a problem can have several solutions.... And there was a trace of the business-world in there too....

> "But since we are constantly being
> exhorted to exercise independence of
> mind and apply scientific methods,
> undoubtedly the best way would be to
> knock on the janitor's door and say to him
> 'If you would like a nice new
> barometer, I will give you this one if you
> tell me the height of this
> building'."

I liked this answer.... it shows Niels Bohr using "leverage" of the value of the barometer to get an answer!

Thanks Simon! :)

- Dien