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J. Perelman
"Entertaining physics". Book 2.
Chapter 2. Power. Work. Friction

IT EASY TO BREAK THE EGG SHELL?

Among the philosophical issues that broke his wise head thoughtfully Cephas makiewicz of "Dead souls", was such a problem: "Well, if the elephant was born in the egg, because the shells, tea, much would be thick was cannon will not proxybase; need some new firearms gun to invent".

Gogol philosopher would, probably, not a little astonished if he knew that ordinary eggshell, despite its subtlety, is also not a gentle thing. Crush the egg between your hands, pressing on its ends, is not so easy; you need a great deal of effort to break the shell under similar conditions (Experience is some danger - shell can be stuck in the hand and requires diligence.).


To break the egg in this position, takes considerable effort.

Such an extraordinary fortress eggshell depends solely on its convex form and is explained as well as the strength of all kinds of vaults and arches.

On the attached picture shows a small stone arch above the window.


The reason for the strength of the arch.

Cargo S (i.e., the weight of the overlying parts of the masonry), pushing up on the wedge-shaped middle stone arch, pressing down with the force denoted by the arrow And. But to move down the stone cannot due to its wedge-shaped form; he only presses on the adjacent stones. The strength And decomposes according to the rule of the parallelogram into two forces, indicated by arrows From and To; they are balanced by the resistance of the adjacent rocks, in turn, sandwiched between adjacent. Thus, the force pressing the vault from the outside, can't destroy. But relatively easy to destroy its force from the inside. This is understandable, since the wedge-shaped stones that prevent them to fall, does not prevent them to rise.

Shell eggs - the same code, only solid. When the pressure outside it collapses is not as easy as you would expect from such a fragile material. You can put pretty heavy table legs on four raw eggs - and they are not rastavatsya (for stability it is necessary to supply eggs at the ends of the plaster extensions; gypsum easily stick to the lime shell).

Now you understand why the hen does not have to be afraid to break the egg shells with the heaviness of his body. And at the same time weak chick, wanting to get out of a natural prison, easily breaks beak shell from the inside.

Easily breaking the egg shell side kick teaspoon, we don't know how durable it is, when pressure is applied to it under natural conditions, and how reliable armor has protected nature developing in her living creature.

The mysterious strength of a light bulb, it would seem so delicate and fragile, is explained as well as the strength of the eggshell. Their fortress will become even more striking if we remember that many of them hollow and not getpane) is almost completely empty and nothing inside was not opposing the pressure of the external air. And the pressure of the air on the light bulb considerable: with diameter 10 cm bulb is squeezed from both sides by the power of more than 75 kg (body weight). Experience shows that the cavity light bulb is able to withstand even 2.5 times more pressure.

Entertaining physics J. Perelman

 




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