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[hillsbororiver]

Great Moments in Physics

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. 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 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 sqroot (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 Bohr, the only person from Denmark to win the Nobel prize for Physics.

[rrammfcitktturjsp]

Joe,

  I LOVE this.  I remember taking a Calculus I final my freshman year in college.  It was a 3 hour final.  After finishing the final, I realized all my answers were wrong.  I asked for another blue book and simply redefined the number system in a matter of 20 minutes.  I then came up with redefined caclulus principles and things of that nature.  I turned in the final with seconds to spare.  I passed with an A+.  The professor was astounded that I would not settle for showing my work again, but redefining the number system.  He said that showed a complete understanding of Caclulus not to mention a few grad courses in math.

  That was the A that I received that semester that meant the most to me.

  Nonconformity, I love it.

  Sincerely,


  Anne C. McGuire

[hillsbororiver]

Hi Anne,

Yes, creative thinking or thinking "outside the box" is an admirable trait.

I loved your example as well, you know I dont think I ever got an "A" in any form of advanced mathmatics except the "a" after the "m" and before the "t"...................

But way back in my machine shop days, we had to master a few Calculus formulas to calculate foot/lbs. pressure/thrust needed to bend (different) metals to a very exact angle, most tolerences were within .005 of an inch. It was actually much easier to comprehend (for me anyway) to see and understand the practical application rather than theory.

His Love and Peace to you,

Joe

[rrammfcitktturjsp]

Joe,

  Hah.  Yeah I could never do the pratical stuff with mathematics.  I am pure theorist.  I wish I could apply my proofs and things, but I do not think outside of the realm of theory.  It baffles me with how to apply these things.

  Sincerely,


  Anne C. McGuire