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


Can I at 8 o'clock in the morning to fly from Vladivostok and 8 o'clock in the morning of the same day to fly to Moscow? This question is not meaningless. Yes, you can. To understand this answer, you only need to remember that the difference between the lap time of Vladivostok and Moscow is nine hours. And if the plane will be able to pass the distance between Vladivostok and Moscow during this time, he will arrive in Moscow in the hour of his departure from Vladivostok.

The distance from Vladivostok to Moscow is about 9000 km Means that the aircraft speed should be equal to 9000 : 9 = 1000 km/hour. This is achievable in modern conditions the speed.

“To overtake the Sun” (or, more accurately, the Earth) in the polar latitudes, need significantly less speed. On the 77th parallel (New Earth) aircraft with a speed of about 450 km/h, flying as much time over the same interval of time to pass the point of the earth surface during the rotation of the Earth around its axis. For a passenger of this plane, the Sun will stop and be still hanging in the sky, not approaching the sunset (of course, the plane must be moving in the right direction).

Even easier to overtake the moon in its revolution around the Earth. The moon moves around the Earth in 29 times slower than the Earth around its axis (compared, of course, the so-called “corner”, and not linear velocity). Therefore, an ordinary steamer, making 25 to 30 km per hour, already in the mid-latitudes to overtake the moon.”

This phenomenon refers to mark TWAIN in his essay “the Simpletons abroad”. During the journey across the Atlantic from new York to the Azores Islands “was the beautiful summer weather and the nights were even better days. We observed a strange phenomenon: the moon that appears every night at the same hour at the same point in the sky. The reason for this is the original behavior of the moon at first remained mysterious for us, but then we realized what we were getting every hour at 20 minutes of longitude to the East, i.e., it is as fast to keep up with the moon!”.

Entertaining physics J. Perelman


System Orphus


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