Supposedly one of the worst problems ever created.
Translation: 上海初中物理题 如此销魂！额滴个神！！！
A bear stumbled into a trap 19.617 meters deep. His falling time was only 2 seconds. What color was this bear?
A. White (polar bear)
D. Black brown, Malay bear
E. Grey bear
Using the classic equation s=gt2/2, it can easily be calculated that g = 9.8085 m/s2. Many people claim this is the acceleration due to gravity at the poles. They are wrong. g at North Pole is 9.832, which is much greater than our value on hand. Even at the equator, g is already 9.780.
I looked up the tabulated values and saw that this particular g corresponds to a latitude of 44o. There are no bears in the southern hemisphere. So, we know the location is 44o N.
The problem statement tells us that the bear fell into a trap and it was a trap large enough to contain him. On land, fewer animals are bigger than the bear. Thus, we can say with confidence that the trap was designed specifically for bears.
In addition, since the trap was on land, we can be sure that this was a terrestrial bear, who has bad vision and does not notice traps easily.
At this point, only B and C make sense.
To be able to create a 19.617 m hole, the soil must be soft enough.
Brown bears are typically located in regions of high elevations. They are ferocious, and the risks of hunting them are great. Furthermore, they are not as valuable, as bear paws and bile are extracted from black bears.
The places where the two types of bears live do not overlap. Thus, the answer should be C.
熵：宇宙的终极规则 - 1、 有人曾经问我："成年后，有没有书籍改变过你的世界观？" 我想了想，还真有这样的书。那时，我已经工作好几年了，偶然在图书馆翻到一本旧书《熵：一种新的世界观》（上海译文出版社，1987）。 那本书是科普著作，介绍物理学概念"熵"。中学毕业后，我再没有碰过物理学，但是没想到读完以后，我看待世界的眼光都变...
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