要有段时间不能来牧夫了(要长距离搬家),给大家个有味道的笑话,鼓励大家“学科学,爱科学”. 这个笑话从一个侧面反映了优秀学生的精彩的物理思维。
^^ ^^ ^^ ^^
How Hot Is It In Hell? (Story from a professor at Yale )
A thermodynamics professor had written a take home exam for his
graduate students. It had one question: Is Hell exothermic (gives off
heat)or endothermic (absorbs heat)? Support your answer with a
proof.
Most of the students wrote proofs of their beliefs using Boyle's Law
(gas cools off when it expands and heats up when it is compressed) or
some variant.
One student, however, wrote the following:
First, we need to know how the mass of Hell is changing in time. So,
we need to know the rate that souls are moving into Hell and the rate
they are leaving. I think that we can safely assume that once a soul
gets to Hell, it will not leave. Therefore, no souls are leaving.
As for how many souls are entering Hell, let's look at the different
religions that exist in the world today. Some of these religions
state that if you are not a member of their religion, you will go to
Hell. Since there are more than one of these religions and since most
people do not belong to more than one religion, we can project that
all people and all souls go to Hell.
With birth and death rates as they are, we can expect the number of
souls in Hell to increase exponentially. Second, we look at the rate
of change of the volume in Hell because Boyle's Law states that in
order for the temperature and pressure in Hell to stay the same, the
volume of Hell has to expand as souls are added.
This gives two possibilities:
1. If Hell is expanding at a slower rate than the rate at which
souls enter Hell, then the temperature and pressure in Hell will
increase until all Hell breaks loose.
2. Of course, if Hell is expanding at a rate faster than the
increase of souls in Hell, then the temperature and pressure will drop
until Hell freezes over.
So which is it?
If we accept the postulate given to me by Miss Theresa Banyan during
my freshman year that "It will be a cold night in Hell before I sleep
with you"; and take into account the fact that I still have not
succeeded with her, then #2 cannot be true, and so Hell is exothermic.
The student got the only A. |
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