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 credits 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 that 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 those were.

"Well," said the student, "there are many ways of getting the height of a tall building with the aid of a barometer. 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. You can also 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 can be calculated. Probably the best way of solving the problem 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. These are Rutherford’s words)

— Aditya Rishi