An insect is not afraid of gravity, but it is in deadly fear of another force

游客2023-09-28  32

问题    An insect is not afraid of gravity, but it is in deadly fear of another force of nature. This force is called surface tension. A man coming out of a bath carries with him a film of water about one fiftieth of an inch in thickness. This weighs about a pound. A wet mouse has to carry its own weight in water. A wet fly has to lift many times its own weight, and as everyone knows, a fly once wetted by water or any other liquid is in a very serious position indeed. An insect going for a drink is in as great danger as a man leaning over the edge of a cliff in search of food. If it once falls into the grip of the surface tension of the water -- that is to say, gets wet -- it is likely to remain so until it drowns. A few insects contrive to be unwettable: The majority keep away from their drink by means of long proboscis.

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答案 surface tension

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