Word
Gems
What is a
man but the sum of his thoughts?
Knowledge:
Niels
Bohr
- Sir Ernest Rutherford (1871-1937), recipient of the Nobel Prize in
Physics: "Some time ago I received a call from a colleague. He was
about to give a student a zero for his answer to a physics question, while the student
claimed a perfect score... I read the examination question:
- "'Show how it is possible to determine the height of a tall building with the aid
of a barometer.'
-
- "The student had answered: 'Take the barometer to the top of the building, attach a
long rope to it, lower it to the street, and then bring it up, measuring the length of the
rope [which is] the height of the building.'
-
- "The student really had a strong case for full credit since he had really answered
the question completely and correctly! On the other hand, if full credit were given, it
could well contribute to a high grade in his physics course and certify competence in
physics, but the answer did not confirm this.
-
- "I suggested that the student have another try.
-
- "I gave the student six minutes to answer the question with the warning that the
answer should show some knowledge of physics. At the end of five minutes, he hadn't
written anything. I asked him if he wished to give up, but he said he had many answers to
this problem; he was just thinking of the best one. I excused myself for interrupting him
and asked him to please go on. In the next minute, he dashed off his answer, which read:
-
- "'Take the barometer to the top of the building and lean over the edge of the roof.
Drop the barometer, timing its fall with a stopwatch. Then, using the formula x = 0.5 * a
* t 2, calculate the height of the building.'
-
- "At this point, I asked my colleague if he would give up. He conceded, and gave the
student almost full credit.
-
- "While leaving my colleague's office, I recalled that the student had said that he
had other answers to the problem, so I asked him what they were.
-
- "'Well,' said the student, 'there are many ways of getting the height of a tall
building with the aid of a barometer. For example, you could take the barometer out on a
sunny day and measure the height of the barometer, the length of its shadow, and the
length of the shadow of the building. and by the use of simple proportion, determine the
height of the building.'
-
- "'Fine,' I said, 'and others?'
-
- "'Yes,' said the student, 'there is a very basic measurement method you will like.
In this method, you take the barometer and begin to walk up the stairs. As you climb the
stairs, you mark off the length of the barometer along the wall. You then count the number
of marks, and this will give you the height of the building in barometer units. A very
direct method.'
-
- "'Of course, if you want a more sophisticated method, you can tie the barometer to
the end of a string, swing it as a pendulum, and determine the value of g [gravity] at the
street level and at the top of the building. From the difference between the two values of
g, the height of the building, in principle, can be calculated.'
-
- "'On this same tack, you could take the barometer to the top of the building,
attach a long rope to it, lower it to just above the street, and then swing it as a
pendulum. You could then calculate the height of the building by the period of the
precession.'
-
- "'Finally,' he concluded, 'there are many other ways of solving the problem.
Probably the best,' he said, 'is to take the barometer to the basement and knock on the
superintendent's door [offering him] a fine barometer as a gift if he will tell you the
height of the building.'
-
- "At this point, I asked the student if he really did know the conventional
answer to this question. He admitted that he did, but said that he was fed up with high
school and college instructors trying to teach him how to think.
-
- "The name of the student was Niels Bohr."
-
- (Niels Bohr, Danish Physicist; Nobel Prize, 1922; best known for proposing the first
'model' of the atom with protons and neutrons, and the various energy states of the
surrounding electrons, the familiar icon of the small nucleus circled by three elliptical
orbits; but more significantly, an innovator in Quantum Theory.)
|