*Sir Ernest Rutherford, President of the Royal Academy, and recipient of*

the Nobel Prize in Physics, related the following 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 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 hadn't 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*t2, 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 [gravity] 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 tack, 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 name of the student was Niels Bohr." (1885-1962) Danish

Physicist; Nobel Prize 1922; best known for proposing the first

'model' of the atom with protons & neutrons, and various energy

state of the surrounding electrons -- the familiar icon of the small

nucleus circled by three elliptical orbits ... but more

significantly, an innovator in Quantum Theory.

the Nobel Prize in Physics, related the following 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 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 hadn't 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*t2, 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 [gravity] 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 tack, 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 name of the student was Niels Bohr." (1885-1962) Danish

Physicist; Nobel Prize 1922; best known for proposing the first

'model' of the atom with protons & neutrons, and various energy

state of the surrounding electrons -- the familiar icon of the small

nucleus circled by three elliptical orbits ... but more

significantly, an innovator in Quantum Theory.