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J. Perelman
"Entertaining physics". Book 2.
Chapter 8. The magnetism. Electricity

MAGNETIC FLYING MACHINE

In the beginning of this book I was referred to an entertaining work of a French writer Cyrano de Bergerac "History of States on the moon and the Sun." In it, among other things, described a curious flying machine, the action of which is based on magnetic attraction and one of the heroes of the story landed on the moon. Give this place works verbatim:

"I ordered the manufacture of a light rail vehicle; entering it and sitting comfortably on the seat, I began to throw high above a magnetic ball. The iron wagon immediately went up. Every time I was close to the place where I drew the ball, I threw it up. Even when I just lifted the ball in his hands, the cart went up, trying to get closer to the ball. After repeatedly throwing the ball up and lifting carts I approached the place where it started from my fall on the moon. And because at this point I firmly held in the hands of the magnetic ball, the cart was leaning against me and never left me. In order not to break the fall, I threw his ball so that the fall of the wagon slowed down its attraction. When I was just two or three hundred yards from the lunar soil, I began to throw the ball at right angles to the direction of fall, until the wagon was not very close to the soil. Then I jumped from the wagon and gently down on the sand."

No one, of course, neither the author nor the readers of his books - no doubt absolutely described a flying machine. But I don't think that many were able to correctly tell me what actually is the reason for the impracticability of this project: because you cannot throw the magnet, while in the iron cart because the cart will not be attracted to the magnet, or something else?

No, throw the magnet can, and he pulled the cart, if strong enough, but still flying machine does no progress would be up.

Did you happen to throw a heavy thing with boats on the shore? You no doubt noticed that the boat itself is moving away from the shore. Your muscles, letting throw things push in one direction, push your body (and with it the boat in the opposite direction. This is the law of the equality of the current and opposing forces, which we have had to say. When throwing magnet, the same thing happens: the rider, tossing magnetic ball up (with great effort, because the ball is attracted to the iron wagon), inevitably pushes the entire vehicle down. When then ball and the cart again converge mutual attraction, they only returned to its original place. It is clear, therefore, that even if the cart weighed nothing, then cast magnetic ball you could tell her only fluctuations around a mean position; to make it this way move progressively impossible.

During the Cyrano (in the middle of XVII century) law of action and reaction has not yet been proclaimed; it is doubtful, therefore, that the French satirist could clearly explain the failure of his humorous project.

Entertaining physics J. Perelman

 




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