Forwarded e-mail... amusing!

The following concerns a question in a physics degree exam at the Universityof 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 thebarometer from the roof of the skyscraper to the ground. The length of thestring plus the length of the barometer will equal the height of thebuilding."

This highly original answer so incensed the examiner that the student wasfailed. The student appealed on the grounds that his answer was indisputably correct, and the university appointed an independent arbiter to decide thecase. The arbiter judged that the answer was indeed correct, but did theproblem it was decided to call the student in and allow him six minutes inwhich to provide a verbal answer which showed at least a minimal familiaritywith 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 studentreplied that he had several extremely relevant answers, but couldn't make uphis 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 = 0.5gx 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 measurethe length of the skyscraper's shadow, and thereafter it is a simple matterof proportional arithmetic to work out the height of the skyscraper."

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

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

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

"But since we are constantly being exhorted to exercise independence of mindand apply scientific methods, undoubtedly the best way would be to knock onthe janitor's door and say to him 'If you would like a nice new barometer, Iwill 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.