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

AMAZING VESSEL

Is it possible to arrange such a vessel from which water flowed all the time a uniform stream, not slowing its flow, despite the fact that the liquid level decreases? After what you learned from the previous articles, you are probably ready to find a similar problem intractable.

Meanwhile, it is quite feasible. The Bank shown in the figure, it was such an amazing vessel. This ordinary Bank with a narrow throat through a tube which is pushed the glass tube. If you open a faucet With a lower end of the tube, the liquid will flow from his unrelenting stream up until the water level falls in the vessel to the lower end of the tube. Udinov tube almost to the level of the tap, you can get all the liquid above the level of the holes to flow evenly, though very weak stream.


The device of the vessel of the MARRIOTT.
From the hole With water flows evenly.

Why is this happening? Watch what takes place in the vessel while open the faucet With. First of all, water is poured out of a glass tube; the liquid level inside of it comes down to the bottom of the tube. Upon further leakage already lowered the water level in the vessel and through a glass tube includes an outer air; it seeps bubbles through the water and going over it in the upper part of the vessel. Now all level In the pressure is atmospheric. Therefore, tap water With flows only under the pressure of the water layer of the sun, because the pressure of the atmosphere inside and outside of the vessel is balanced. As well as the thickness of the armed forces remains constant, and it is not surprising that the jet flowing all the time with the same speed.

Try now to answer the question: how fast will follow the water, if you take the cork In level end of the tube?

It turns out that it does not leak (of course, if the hole is so small that its width can be neglected; otherwise the water will flow under the pressure of a thin water layer thickness in the width of the hole). In fact, here on the inside and outside pressure is atmospheric, and nothing encourages water to flow.

And if you pulled out the cork And above the lower end of the tube, not only the water is not leaking from the vessel, it still would have outside air. Why? For a very simple reason: within this part of the vessel, the air pressure is less than atmospheric pressure outside.

This vessel with such extraordinary properties was invented by the famous physicist MARRIOTT and named for the scientist "vessel of the MARRIOTT hotel.

Entertaining physics J. Perelman

 




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