A
bit of Lateral Thinking or "How to determine the height
of a skyscraper with a barometer?"
'The following 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:
"You 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 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 sqr 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 skyscraper."
The student was Niels Bohir, the
only Dane to win the Nobel prize for Physics.
Jokes
to amuse - I hope!