Here is something a friend forwarded. I have read it before but found it really worth reading.
Here’s a story….
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. The instructor and the
student agreed to an impartial arbiter, and I was selected.
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. The length of
the rope 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 to 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 had not written anything. I asked 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 andlean 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 ther 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 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 tact, 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.
When the superintendent answers, you speak to him as follows:
‘Mr. Superintendent, here is a fine
barometer. If you will tell me the height of the building, I will
give you this barometer.”
At this point, I asked the student if he really did not 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 student was Neils Bohr (quantum theory & physics & mechanics,
hydrogen atom guru etc ) and the arbiter Rutherford.
THINK DIFFERENT!!!!
