## Think Differently…

Once a professor 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 he was selected.He 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 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 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 and the arbiter

Rutherford.

THINK DIFFERENT…!!!!

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