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J. Perelman
"Entertaining physics". Book 2.
Chapter 6. Properties of liquids and gases


Who moved closer to the center of the Earth - not in the imagination of the novelist, and in reality? Of course, the miners. We already knowthat the deepest mine in the world dug in South Africa. She goes back more than 3 km. Here does not mean the depth of penetration of the drill bit, reaching 7.5 km, and the deepening of the people themselves. That says, for example, on mine on mine Morro Velho (depth of about 2300 m) French writer Dr. Luke Duran, personally visited her:

"The famous gold mines Morro Velho are 400 km from Rio de Janeiro. After 16 hours away by rail in rocky terrain you down into a deep valley, surrounded by jungle. Here, the company is developing a gold-bearing veins at such a depth, which never descended people.

Lived goes deep into the obliquely. Mine follows six ledges. Vertical shaft - wells, horizontal tunnels. Extremely characteristic of modern society that the deepest pit dug into the crust of the globe, is the most ambitious attempt of man to penetrate into the bowels of the planet - made in search of gold.

Put on canvas overalls and leather jacket. Be careful: the smallest pebble falling into the well, can hurt you. We will be accompanied by one of the "captains" of mine. You enter the first tunnel, well-lit. You began to tremble from the icy wind at 4°: ventilation for cooling the depths of the mine.

Driving in narrow metal cage first well at a depth of 700 m, you get to the second tunnel. Down in the second well; the air becomes warmer. You are already below sea level.

Starting from the next well, the air burns the face. Sweating, bent under the low arch, you bodygames towards Reba drilling machines. In the thick dust are naked people; with them with sweat, hands continuously transmit a bottle of water. Do not touch the fragments of ore, now broken away: their temperature is 57°.

What is the result of this horrible, disgusting reality? About 10 kilograms of gold per day...".

Describing the physical conditions at the bottom of the mine and the extreme exploitation of the workers, the French writer notes the high temperature, but does not mention the increased air pressure. Calculate what it is at a depth of 2300 m If the temperature remained the same as on the Earth's surface, according to the already familiar to us the formula, the density of air would rise in


In fact, the temperature does not remain constant, but increased. Therefore, the air density grows less and less. Ultimately, the air on the bottom of the mine density varies from the air on the Earth's surface little more than an air of sultry summer day from the frosty winter air. It is clear now why it has not attracted the attention of the visitor mine.

But the great value has a significant humidity in such deep mines, making them stay in unbearable at high temperature. In one of the South African mines (Johanesburg), depth 2553 m, humidity at 50° heat reaches 100%; it is arranged now so-called "artificial climate, and the cooling effect of the installation ravnoznachen 2000 tons of ice.

Entertaining physics J. Perelman


System Orphus


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