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J. Perelman
"Entertaining physics". Book 1.
Chapter 1. Speed. The addition of movements


In the Paris Newspapers appeared once the ad promised each 25 centimes to specify how to travel cheaply and then without the slightest fatigue. There was gullible, who sent the required 25 centimes. In response, each of them received a letter in the mail with the following content:

“Stay, citizen, quietly in my bed and remember that our Earth is spinning. On Parallels Paris - 49th - you do every day more than 25 000 km And if you like scenic views, fold the window curtain and admire the painting of the starry sky”.

Taken to court for fraud, the perpetrator of this invention listened to the verdict, paid imposed on him a fine and, say, becoming and theatrical pose, solemnly repeated Galileo's famous exclamation:

And yet it does move!

In a sense, the accused was right, because every inhabitant of the globe not only traveling, revolving around the earth's axis, but with greater speed tolerated by the Earth in its revolution around the Sun. Every second our planet with all its inhabitants moved in the space of 30 km, rotating simultaneously around the axis.

On this occasion, you can ask an interesting question: when we move around the Sun faster - day or night?

The question is likely to cause confusion: it is always on one side of the Earth day, the other night; what sense is our question? Apparently, no. However, this is not the case. The question is why, not how, when all the Earth is moving soon, and that when we, its inhabitants, are moving rather among the stars. And this is not a meaningless question. In the solar system, we performed two movements: rotate around the Sun and at the same time turn around the earth's axis. Both movements are formed, but the result is different, it all depends whether we are on day or night half of the Earth. Look at the picture and you will realize that at midnight the speed of rotation is added to the translational velocity of the Earth, and at noon, on the contrary, is subtracted from it. Then at midnight we are moving in the solar system faster than at noon.

On the night half of the globe people are moving around the Sun faster than a day.

Because the point of the equator run through a second about a mile, to the Equatorial strip the difference between midday and midnight speed reaches a kilometer per second. Familiar with the geometry can easily calculate that for Leningrad (which is on the 60th parallel) this difference is less than twice: at midnight Leningraders every second run in the solar system half a kilometer more than at noon.

Entertaining physics J. Perelman


System Orphus


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