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


Hopeless pursuit of the “eternal” engine many people did deeply unhappy. I knew working, invested all his earnings and savings on manufacturing model “eternal” engine came as a result to complete poverty. He became a victim of its unworkable ideas. Half-dressed, always hungry, he asked everyone to give him the money to build the “final model”, which is already “will move”. It was sad to realize that this man suffered deprivation is solely due to poor knowledge of the elementary foundations of physics.

Interestingly, if you search for “eternal” engine always turned out to be fruitless, then, by contrast, a deep understanding of its impossibility has often led to fruitful discoveries.

A great example would be the method by which Stevin, great Dutch scholar of the late sixteenth and rocked the XVII century, discovered the law of equilibrium of forces on an inclined plane. This mathematician deserves much more publicity than that which has fallen to his share, because he made many important discoveries that we now use regularly: invented decimal, introduced in algebra the use of indicators, opened the hydrostatic law, subsequently re-opened Pascal.

The law of equilibrium of forces on an inclined plane, he opened not based on the rule of parallelogram of forces, it is only with the help of the drawing, which is here reproduced.

“The miracle is not a miracle.”

Through the triangular prism thrown a chain of 14 identical balls. What will happen with this circuit? The lower part of the hanging garland, balanced by itself. But the other two parts of the circuit - balance whether each other? In other words: the right two balls are balanced if left four? Of course, Yes, " otherwise the circuit itself ever would have fled from right to left because the place slipped balls every time would fit other and the balance would never have recovered. But since we know that the chain, thrown this way, not moving by itself, then, obviously, the two on the right of the ball really balanced four left. It turns like a miracle: two balls are pulling with the same force as four. From this seeming miracle, Steven brought important law of mechanics. He reasoned. Both chain and long and short - weigh differently: one chain is heavier than the other at the same time, many times the long face of the prism longer short. This implies that in General two weights connected by a cord, balance each other on inclined planes, if the weights are proportional to the lengths of these planes.

In the particular case when a short vertical plane, we obtain the well-known law of mechanics: in order to keep the body on an inclined plane, it is necessary to act in the direction of the plane power, which in many times less than the weight of the body, many times the length of the plane more of its height.

So, based on the thought of the impossibility of perpetual motion, was made an important discovery in mechanics.

Entertaining physics J. Perelman


System Orphus


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