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J. Perelman
"Entertaining physics". Book 2.
Chapter 1. The basic laws of mechanics

WHY ROCKET TAKES OFF?

Even among people who have studied physics, happens often to hear a very perverse explanation missile: it flies because if that their gases from the combustion therein of gunpowder, is repelled from the air. I thought so in the old days (rocket - old invention). However, if you put a rocket in outer space, she'd not worse, and even better than in the air. The true cause of the motion of the rocket is quite different. Very clear and simply laid out its revolutionary perfomative Kibalchich to death in his Memorandum about he invented a flying machine. Explaining the device of missiles, he wrote:

"In a tin cylinder, closed at one base and open with the other, is inserted into a tight cylinder of compacted powder having an axis emptiness in the form of a channel. Burning gunpowder begins with the surface of the channel and extends over a certain period of time until the outer surface of the pressed powder; from the combustion gases to produce a pressure in all directions; but the lateral pressure gases are mutually balanced, the pressure on the bottom of the tin shell powder, not balanced by an opposite pressure (as in this way the gases are free exit), pushes the rocket forward."

Here is the same as if shot from a gun: the bullet flies forward, and the gun pushes back. Remember the "return" guns and all General firearms! If the gun hung in the air, no leaning, after she shot would move back with some speed, which is as many times smaller than the velocity of the projectile, how many times the projectile easier the gun. In a fantasy novel by Jules Verne "Upside down" the Americans have planned even use the force of bestowal giant cannon to perform a Grand idea - "to straighten the axis of the earth".

Rocket - the same gun, only spews it is not the shells and powder gases. For the same reason revolves and the so-called "Chinese wheel", which probably happened to you to enjoy at the firework display device: when burning powder in the tubes attached to the wheel, the gases flow in one direction, the tube (and the wheel) get return movement. In fact, it is only a modification of the well-known physical device - Saharova wheels.

It is interesting to note that before the invention of the steamboat, there was a project mechanical vessel, based on the same beginning; supply of water on the ship was supposed to throw with strong injection pump in aft; as a result, the ship had to move forward as the floating cans, which are available for proof of the principle in high school physics classrooms. This project (proposed Ramsey) was not implemented, however, he played a famous role in the invention of the steamboat, as suggested Coles on his idea.

We also know that the oldest steam engine, invented by Heron of Alexandria in the second century BC, was built on the same principle: the steam from the boiler is admitted through the pipe into a ball, mounted on a horizontal axis; then emerging from the crankshaft is bent tubes, steam pushed these tubes in the opposite direction, and the ball began to spin.


The oldest steam engine (turbine), attributed to Heron of Alexandria
(II century BC).

Unfortunately, geronova steam turbine in ancient times there was only a curious toy, as the cheapness of slave labor did not encourage the practical use of machines. But the principle is not abandoned appliances: nowadays it is used when the device jet turbines.

Newton is the author of the law of action and reaction is attributed to one of the earliest projects of the steam car, based on the same beginning, the steam from the boiler, put on wheels, pulled to one side, and the boiler in the power of giving is rolling in the opposite.


Steam car, attributed to Newton.

Rocket cars, about the experiences that in 1928, wrote many articles in Newspapers and magazines, is a modern modification of Newtonian carts.

For those who like to do the drawing paper steamer, also very similar to the Newtonian cart: in the steam boiler of the emptied egg, heated soaked in alcohol fleece in the thimble, is formed pairs; the escaping stream in one direction, it causes the entire ship to move in the opposite direction. For a construction of this instructive toys are needed, however, very skilled hands.


Toy boat out of paper and eggshell. Fuel is poured into the thimble alcohol.
Couples standing out of the hole "steam boiler" (blown egg), causes the boat to sail in the opposite direction.

Entertaining physics J. Perelman

 




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