A university lecturer turned to Sir Ernest Rutherford, President of the Royal Academy and Nobel Prize winner in physics, for help. He was about to give the lowest grade in physics to one of his students, while he claimed that he deserved the highest grade. Both teacher and student agreed to rely on the judgment of a third party, a disinterested arbitrator. The choice fell on Rutherford. The exam question read: “Explain how you can measure the height of a building using a barometer?”
The student’s answer was: “You need to go up to the roof of the building with a barometer, lower the barometer down on a long rope, and then pull it back and measure the length of the rope, which will show the exact height of the building.”
The case was truly complicated, since the answer was absolutely complete and correct! On the other hand, the exam was in physics, and the answer had little to do with the application of knowledge in this field.
Rutherford asked the student to try again. Giving him six minutes to prepare, he warned him that his answer must demonstrate knowledge of physical laws. After five minutes, the student still had not written anything on the exam paper. Rutherford asked him if he was giving up, but he stated that he had several solutions to a problem and was simply choosing the best one.
Interested, Rutherford asked the young man to begin answering without waiting for the allotted time to expire. The new answer to the question read: “Climb to the roof with a barometer and throw it down, timing the fall. Then use the formula to calculate the height of the building.”
Here Rutherford asked his teaching colleague if he was satisfied with this answer. He finally gave in, recognizing the answer as satisfactory. However, the student mentioned that he knew several answers and was asked to reveal them.
“There are several ways to measure the height of a building using a barometer,” the student began. “For example, you can go outside on a sunny day and measure the height of the barometer and its shadow, and also measure the length of the shadow of a building. Then, having solved a simple proportion, determine the height of the building itself. “Not bad,” said Rutherford. — Are there other ways?
- Yes. There is a very simple way that I am sure you will like. You take the barometer in your hands and walk up the stairs, placing the barometer against the wall and making marks. By counting the number of these marks and multiplying it by the size of the barometer, you get the height of the building. Quite an obvious method.
“If you want a more complicated method,” he continued, “then tie a string to a barometer and, swinging it like a pendulum, determine the magnitude of gravity at the base of the building and on its roof.” From the difference between these values, in principle, it is possible to calculate the height of the building. In the same case, by tying a string to the barometer, you can climb onto the roof with your pendulum and, swinging it, calculate the height of the building from the precession period.
“Finally,” he concluded, “among many other ways to solve this problem, perhaps the best is this: take the barometer with you, find the manager and tell him: “Mr. Manager, I have a wonderful barometer. It is yours if you tell me the height of this building.”
Here Rutherford asked the student whether he really did not know the generally accepted solution to this problem. He admitted that he knew, but said that he was fed up with schools and colleges where teachers impose their way of thinking on students.
This student was Niels Bohr (1885–1962), Danish physicist, Nobel Prize winner in 1922.
Translated from Russian · original on wisdomlib.ru