the story of a genius NEILS BOHR

The teacher asks a student how he would measure the height of a very tall
building using a barometer, evidently expecting to hear about the
reduced air pressure being proportionate to the elevation ....

The student says: Tie the barometer to a long string, lower the string
till the barometer touches the ground, measure the length of the string!

However, what follows is much more interesting:

This highly original answer so incensed the examiner that the student
was
failed. The student 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 a 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
square 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, 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 skyscraper'."

The student was Niels Bohr, the only person from Denmark to win the
Nobel
prize for Physics.