Site for children

J. Perelman
"Entertaining physics". Book 1.
Chapter 6. Thermal phenomena


On the line Leningrad - Moscow every winter disappear completely without a trace a few hundred metres expensive telephone and Telegraph wire, and no one is concerned, though the cause of the disappearance of well-known. Of course, you know him: the thief this is frost. What we talked about railscan be applied to the wire, with the only difference that the copper telephone wire extends from the warmth 1.5 times greater than steel. But here there are no gaps, and because we are without any reservations can be argued that the telephone line Leningrad - Moscow in the winter on 500 meters shorter than in summer. Frost with impunity every winter steals almost half a kilometer of wire, without, however, any disturbances in the operation of the telephone or Telegraph, and gently returning stolen when warm time.

But, when this compression from the cold is not with wires and bridges, the consequences are often very noticeable. Here is what was reported in the December, 1927, the newspaper about a similar case:

“Extraordinary to France frosts standing for several days, caused serious damage to the bridge over the Seine, in the heart of Paris. The iron skeleton of the bridge from the cold sank, causing swollen and then crumbled cubes by covering the pavement. The bridge is temporarily closed”.

Entertaining physics J. Perelman


System Orphus


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