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J. Perelman
"Entertaining physics". Book 2.
Chapter 7. Thermal phenomena

ALWAYS BOILING HOT?

Brave orderly Ben Sup with which the reader, no doubt, met on the novel by Jules Verne "Hector Servadac", was firmly convinced that the boiling water is always and everywhere equally hot. He probably would have thought so, throughout life, if the occasion is not pleased to throw it, along with commander Servicecom... the comet. This whimsical light, collided with the Earth, cut off from our planet just at the point where he was both hero and took them further along their elliptical path. And then Batman was first found that the boiling water does not always equally hot. He made this discovery suddenly, preparing Breakfast.

"Ben SWF poured water into a saucepan, set it on the stove and waited for the water boils to lower her eggs, which seemed empty, so they are not weighed.

Less than two minutes, the water is already boiling.

- Damn it! As the fire heats now! - exclaimed Ben Souf.

- No fire warms stronger, " he replied, thinking, Servadac, and the water boils quickly.

And, removing from the wall thermometer Celsius, he dropped it in boiling water.

The thermometer showed only sixty-six degrees.

- GRT! exclaimed the officer. Water boils at sixty-six degrees instead of a hundred!

"So, captain?...

"So, Ben Sup, we advise you to keep the eggs in boiling water for a quarter of an hour.

"But they'll be cool!

"No, buddy, they will hardly be welded.

The reason for this phenomenon was, obviously, reducing the height of the atmospheric envelope. Air column above the soil surface decreased by approximately one third, and that's why the water is exposed to a lower pressure, boiling at sixty-six degrees instead of a hundred. A similar phenomenon would have occurred on the mountain, which reaches a height of 11,000 feet, And if the captain was a barometer, he would have pointed him this decrease in air pressure".

Observations of our heroes we are not going to question: they say that the water was boiling at 66 degrees, and we'll accept it as a fact. But it is doubtful that they could feel good in the rarefied atmosphere in which they were located.

The author of "Servadac" rightly observes that a similar phenomenon would be observed at a height of 11000 m: there is water, as can be seen from calculation*really should boil at 66°. But the pressure of the atmosphere must be equal to 190 mm Hg, exactly four times less than normal. In the air, rarefied to such an extent that it is almost impossible to breathe! Because we are talking about the heights that are already in the stratosphere! We know that pilots reaching such heights without masks, lost consciousness from lack of air, and meanwhile Servadac and his orderly felt bad. Well that Servadac at hand there was no barometer: otherwise, the novelist would have had to make this tool to show the wrong number, he would have to show according to the laws of physics.

If our heroes were not on the imaginary comet and, for example, on Mars, where the atmospheric pressure does not exceed 60 - 70 mm, they'd have to drink even less hot boiling water is 45 degrees!

On the contrary, very hot boiling water can be obtained at the bottom of deep mines where the air pressure is significantly greater than at the Earth's surface, In mine with a depth of 300 m water boils at 101°, at a depth of 600 m at 102°.

At a much higher pressure water begins to boil and the steam boiler of the machine. For example, at 14 atmospheres water boils at 200 degrees! On the contrary, under the bell, air pump, you can get rapidly boiling water at ordinary room temperature. getting a "boiling" of all degrees 20.

* In fact, if, as we said earlier, the boiling point of water falls to 3° C by raising every kilometer, to lower the boiling temperature to 66° to rise to 34 : 3 = about 11 km.

Entertaining physics J. Perelman

 




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