14.0114 a charming story

From: Humanist Discussion Group (willard@lists.village.virginia.edu)
Date: Fri Jul 14 2000 - 06:47:06 CUT

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                   Humanist Discussion Group, Vol. 14, No. 114.
           Centre for Computing in the Humanities, King's College London

             Date: Fri, 14 Jul 2000 07:45:00 +0100
             From: "Dr Donald J. Weinshank" <weinshan@cse.msu.edu>
             Subject: Measuring the height of a building with a barometer.

    Fellow Humanists:

    The following charming story has been circulating in print and via E-mail
    for decades, but, recently, has developed a new twist.

    Great Moments in Physics

    The following concerns a question in a physics degree exam.

    "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 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

    "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'."


    This is a lovely example of "thinking out of the box" and has been
    widely circulated.

    Recently, however, I have received several copies of the story with two

    1. The story is set at the University of Copenhagen.
    2. The following "tag line" has been added:

            The student was Niels Bohr, the only person from
            Denmark to win the Nobel prize for Physics.
    If true, this would not be entirely surprising. After all,
    the battles between Bohr and Einstein at
    the Solvay conferences in the late '20's hinged
    on such "gedankenexperimenten" covering their
    disagreements. Bohr was one of the champions of
    quantum mechanics. Einstein always felt that "God
    does not play dice" and that there had to be a deeper,
    underlying mechanism, not simply random chance.

    Be that as it may, can anyone authenticate the story
    as being attributable to Bohr?

    Dr. Don Weinshank weinshan@cse.msu.edu
    Phone (517) 353-0831 FAX (517) 432-1061
    Computer Science & Engineering Michigan State University

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