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

HOW QUICKLY WE GO FROM HERE?

Sporting a distance of 1.5 miles good runner runs for about 3 minutes, 50 seconds. (world record 1958 - 3 minutes to 36.8 sec.*). For comparison with the normal walking speed of 1.5 meters per second - it is necessary to do a little calculation, then it will appear that the athlete runs over 7 meters per second, However, the speed of these is not quite comparable: a pedestrian can walk long hours, making 5 km per hour, the athlete is able to maintain a considerable rate of running only a short time. Infantry military unit moves Jogging three times slower than the record; it does 2 meters per second, or 7-odd miles an hour, but is before the athlete the advantage that can make a much larger transitions.

It is interesting to compare the normal gait of a man with the speed of such is included in the adage - slow animals, like a snail or a turtle. Snail justifies the reputation ascribed to her by saying she is 1.5 mm per second, or 5.4 m per hour - exactly one thousand times smaller than human! Another classically slow animal, turtle, not much surpasses a snail: it is the normal speed of 70 meters per hour.

Prompt next to the snail and the turtle, the person will appear before us in a different light, if you compare his movement with others, not even very fast movements in the natural environment. However, it easily surpasses the flow of water in most lowland rivers and not far behind moderate wind. But fly, flying 5 meters per second, a person can successfully compete only on skis. Hare or a hunting dog people will not overtake even on a horse quarry. To compete in speed with the eagle people can only by plane.

Machines invented by man, making it the fastest creature in the world.

Relatively recently in the USSR was built passenger ship with underwater wings, which can reach speeds of 60 - 70 km/h. On land the person can move faster than the water. On some roads the speed of passenger trains in the USSR reaches 100 km/h. New passenger car ZIL-111 can reach speeds of up to 170 km/hour, seven-seater passenger car “Seagull” - up to 160 km/hour.**

These speeds are far superior to modern aviation. On many lines of the Civil air fleet of the USSR work bench the TU-104 and TU-114. The average speed of their flight is about 800 km/h. Not so long ago, before the aircraft was intended to break the “sound barrier”, to exceed the speed of sound (330 m/s, i.e., 1200 km/h). Now this problem is solved. The speed of a small aircraft with a powerful jet engines closer to 2000 km/h***.

The devices created by man, can achieve even higher speeds. Artificial Earth satellites, flying near the border of the dense layers of the atmosphere, moving at a speed of about 8 km/sec. Spacecraft traveling to the planets of the solar system, you receive an initial velocity greater than the escape velocity (11.2 km/sec, at the Earth's surface).

The reader can view the following table speeds:

Object Speed /sec Speed /hour
Snail 1.5 mm/sec 5.4 m/h
Turtle 20 mm/sec 70 m/h
Fish 1 m/s 3.6 km/h
Pedestrian 1.4 m/sec 5 km/h

Cavalry step
Cavalry trot

1.7 m/s
3.5 m/sec

6 km/h
12.6 km/hour

Fly 5 m/s 18 km/h
Skier 5 m/s 18 km/h
Cavalry quarry 8.5 m/sec 30 km/h
Ship with underwater wings 16 m/s 58 km/h
Hare 18 m/s 65 km/h
Eagle 24 m/s 86 km/h
Hunting dog 25 m/s 90 km/h
Train 28 m/s 100 km/h
The ZIL-111 50 m/s 170 km/h
Racing car (record)** 174 m/s 633 km/h
TU-104 220 m/sec 800 km/h
The sound in the air 330 m/s 1200 km/h
Easy jet 550 m/sec 2000 km/hour
The earth in its orbit 30 km/sec 108000 km/h

* Absolute world record, set in 1998, 3 minutes and 26 seconds.
** The maximum speed of a modern car - 431 km/h the record set in 2010, on the model of the Bugatti Veyron 16.4 Super Sport.
*** Currently, military jet aircraft speeds of up to 3500 km/H.

Entertaining physics J. Perelman

 




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