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J. Perelman
"Entertaining physics". Book 2.
Chapter 3. Circular motion


For lovers of strong sensations sometimes gets very peculiar entertainment - the so-called "devil's swing". There was such a swing in Leningrad. I didn't have myself on her swing, but because here is her description of the collection of scientific amusements, pedo:

"The swing is suspended from strong horizontal crossbar, thrown across the room at a known height above the floor. When all sit, especially assigned to that Minister locking the front door, removes plaque, which served as the entrance, and, stating that he will now allow viewers to make a small air journey begins gently rocking the swing. After that he sits behind the swing, like the driver on the carriage, or completely out of the room.

Meanwhile, the magnitude of the swings become more and more; she, apparently, rises to the height of the crossbar, then goes for it, higher and higher, and finally, describes a full circle. The movement is accelerating more and more obvious, and swinging, although for the most part already been warned, have an undoubted sense of swing and fast movements; they think that they are upside down in space, so involuntarily reach for the seat backs, so as not to fall.

But the swings start to decrease; the swing is no longer ascends to the height of the crossbar, and after a few seconds stops completely.

Diagram of the device "devil's swing".

In fact, the swing all the time hung still, until the continued experience, and the room itself, using a very simple mechanism, addressed by spectators around the horizontal axis. Different kinds of furniture attached to the floor or the walls in the room; the lamp is soldered to the table so that it seems easy to turn, consists of an electric light bulb, hidden under a large hood. The Minister, who, apparently, was rocking swing, giving her a light shove, in essence, soopasoul them with light fluctuations of the hall and did just type that oscillates. The whole atmosphere contributes to the overall success of deception".

The secret of the illusion, as you can see, simple to the ridiculous. And yet, if now, already knowing what was happening, you were on "devil's swing", you will inevitably give in to deception. Such is the power of illusion!

Remember Pushkin's poem "the Movement"?

- There is no movement, " said the sage brodaty *.
Another ** kept silent and stood before them.
Stronger if he could not argue.
Praised all response intricate.
But, gentlemen, this fun event
Another example on memory leads me:
Because every day above us the Sun goes
However, the rights stubborn Galileo!

Among the passengers of the swing, not initiated into the secret, you were kind of a Galileo - only in reverse: Galileo proved that the Sun and fixed stars, and whirl, despite the evidence, we do; you will have to prove that we fixed, and the whole room revolves around us. It is possible that you have had this experience and the sad fate of Galileo; you would look like on humans, arguing against the obvious things...


* The Greek philosopher Zeno of Elea (V century BC), who taught that everything in the world is stationary and that only because of the deception of the senses we feel that any body moving.
** Diogenes

Entertaining physics J. Perelman


System Orphus


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