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 and lean over the edge of

the roof. Drop the barometer, timing its fall with a stopwatch. Then, using

the formula H = 1/2 x a x 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.

*DO YOU KNOW WHO THIS STUDENT WAS ........*

The student was *Neil Bohr* (known for quantum theory of physics &

mechanics, hydrogen atom etc) *THINK DIFFERENT ! ! ! !*