[1903] in Humor
HUMOR CLASSIC: The Barometer
daemon@ATHENA.MIT.EDU (abennett@MIT.EDU)
Mon Feb 17 22:46:44 1997
From: <abennett@MIT.EDU>
To: humor@MIT.EDU
Date: Mon, 17 Feb 1997 22:33:39 EST
This is another story that has mutated a bit over the years, but no matter
what the form, it's still a classic.
-Drew
From: "Mark A. Herschberg" <hershey@MIT.EDU>
From: "David Nieves" <nieves@mail.med.upenn.edu>
From: snickers <sseo@mail.med.upenn.edu>
Date: Wednesday, February 12, 1997 1:29 PM
A young man was being interviewed for entrance to Cambridge college to
study physics. He was asked among other things, the following
question: How would you measure the height of a skyscraper using a
barometer?
The candidate replied as follows: Take a very long piece of string.
Tie one end of it to the barometer. Keeping hold of the other end,
dangle the barometer off the roof of the skyscraper until it reaches
the ground. Then the length of the string plus the length of the
barometer equals the height of the skyscraper. The interviewing
tutors did not accept the answer, and the candidate was rejected. But
he appealed to the university authorities on the grounds that his
answer while perhaps unorthodox, was undeniably correct.
It so happened that professor Iza Conman of Michigan was in Cambridge
at the time as visiting professor, and he was asked to arbitrate in
the dispute. He asked the candidate to see him, and gave him five
minutes to reply to the same question in a way that showed knowledge
of the basic principles of physics. The young candidate was silent
for three minutes. Conman warned him that the time was running out.
"The problem is," said the candidate, "I've thought of several
possible answers, but I can't decide which is the best."
"One minute," said Conman. "Well," said the candidate, "You could
take the barometer to the roof of the building and drop it, using a
stopwatch to measure the time the barometer took to reach the ground.
If this t is time, and the acceleration due to gravity is g, then the
height of the building would be gt/2. (editor's note: neglecting
friction and lift.) But then you've got an ex-barometer.
"If the sun is shining, you could measure the length of the barometer,
the length of its shadow, and the length of the skyscraper's shadow.
Then it's just a matter of proportional arithmetic to work out the
height of the sky scraper.
"If you want to be highly scientific you could tie a piece of string
to the barometer and make it swing like a pendulum, first on the roof
and then on the ground. Then you could work out the acceleration due
to gravity on the roof and on the ground from the period of the
oscillation of the pendulum. From this difference you can determine
the height of the building.
"Or you could walk up the stairs with the barometer and a pencil,
marking off lengths of the barometer as you go. Adding them up at the
end."
"If you want to be boring you could measure the air pressure on the
roof and at ground level, convert millibars to meters and get the
height of the sky scraper from that.
"But in the end the best method would probably be to knock on the
janitor's door and say, `Look; if you tell me how high this building
is, I'll give you this lovely new barometer.'"
