The Student and The Barometer

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*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,if the sun is shining you could measure the height of the barometer, then set it on end and measure the length of its shadow. Then you measure the length of the skyscraper's shadow, and thereafter it is a simple matter of proportional arithmetic to work out the height of the skyscraper.

"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, who later received the Nobel prize for Physics.

Boys and Girls
"Equal" is not always synonymous with "the same." Men and
women are created equal. But, boys and girls are not born the
same.

1. You throw a little girl a ball, and it will hit her in
the nose. You throw a little boy a ball, and he will try to
catch it. Then it will hit him in the nose.

2. You dress your little girl in her Easter Sunday best, and
she'll look just as pretty when you finally make it to church
an hour later. You dress a boy in his Easter Sunday best, and
he'll somehow find every mud puddle from your home to the
church, even if you're driving there.

3. Boys' rooms are usually messy. Girls' rooms are usually
messy, except it's a good smelling mess.

4. A baby girl will pick up a stick and look in wonderment
at what nature has made. A baby boy will pick up a stick and
turn it into a gun.

5. When girls play with Barbie and Ken dolls, they like to
dress them up and play house with them. When boys play with
Barbie and Ken dolls, they like to tear off their
appendages.

6. Boys couldn't care less if their hair is unruly. If their
bangs got cut a quarter-inch too short, girls would rather
lock themselves in their room for two weeks than be seen in
public.

7. Baby girls find mommy's makeup and almost instinctively
start painting their face. Baby boys find mommy's makeup and
almost instinctively start painting the walls.

8. If a girl accidently burps, she will be embarrassed. If a
boy accidently burps, he will follow it with a dozen fake
belches.

9. Boys grow their fingernails long because because they're
too lazy to cut them. Girls grow their fingernails long - not
because they look nice - but because they can dig them into a
boys arm.

10. Girls are attracted to boys, even at an early age. At an
early age, boys are attracted to dirt.

11. By the age of 6, boys will stop giving their dad kisses.
By the age of 6, girls will stop giving their dad kisses
unless he bribes them with candy.

12. Most baby girls talk before boys do. Before boys talk,
they learn how to make machine-gun noises.

13. Girls will cry if someone dies in a movie. Boys will cry
if you turn off the TV after they've watched "Teenage Mutant
Ninja Turtles" movie three times in a row.

14. Girls turn into women. Boys turn into bigger boys.