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J. Perelman
"Entertaining physics". Book 1.
Chapter 4. Rotation. "Perpetual motion machines"


Open the umbrella, uprite the end of the floor and rotate the handle; you will not be difficult to give it a fairly rapid movement. Now throw the umbrella inside the ball or crumpled paper; the dropped item does not remain in the umbrella, and will be kicked out for it, which is correctly called “centrifugal force” and that in reality there is only the manifestation of inertia. The ball is not thrown in the direction of radius and tangent to the circular path of movement.

This effect rotational motion based device is a kind of entertainment - “wheel of fun”, which can be seen, for example, in the parks of culture. Visitors have here a case for themselves to test the effect of inertia. The audience is placed on a round platform - standing, sitting, lying, who as wants. Hidden under the ground the motor smoothly rotate it about a vertical axis, first slowly, then faster, gradually increasing the speed. And then under the action of inertia are all on the platform begin to slide to the edges. First, this movement is barely noticeable, but as “passengers” are removed from the centre and fall on the circle larger and larger radius, speed, and hence the inertia of the motion effect more noticeable. No efforts to keep the place does not lead to anything, and people will be reset with the “wheel of fun”.

“Wheel of fun”. People on the rotating circle discarded for its edges.

The globe is, in essence, the same “wheel of fun”, only giant size. Earth, of course, does not relieve us from ourselves, but it still reduces our weight. At the equator, where the speed is greatest, reducing weight from this reason, comes to 1/300 share. And with another reason (compression of the Earth) the weight of each body at the equator decreases, in General, by half a percentage point (i.e., 1/200), so that an adult weighs on the equator approximately 300 g less than at the pole.

Entertaining physics J. Perelman


System Orphus


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