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J. Perelman
"Entertaining physics". Book 1.
Chapter 2. Gravity and weight. A lever. Pressure


Those who have read mentioned now the novel by Jules Verne, interesting that memorable moment of the journey, when the projectile has passed through the point where the gravity of Earth and moon in the same way. Here was something really fantastic: all the items inside the projectile has lost its weight, and the travelers, jumping, hanging in the air without support.

Described it exactly right, but the novelist has overlooked that the same has been observed also before and after a flight through the point of equal attraction. It is easy to show that travelers and all objects inside the projectile should become weightless from the first moment of free flight.

It seems incredible, but I'm sure now you will wonder what you did not notice before such a major omission.

Let's use the example from the novel by Jules Verne. Without a doubt, you have not forgotten how the passengers threw him out of the corpse of the dog and how they were surprised to notice that he does not fall to the Ground, and continues to rush forward together with the shell. Novelist correctly described this phenomenon and gave him the correct explanation. Indeed, in the void, as you know, all bodies fall with the same speed: the attraction of the Earth tells all bodies have the same acceleration. In this case and the projectile, and cadaver dogs were under the influence of gravity to buy the same rate of fall (the same acceleration); rather, the rate that was reported to them at the departure from the gun, was under the influence of gravity to decrease the same. Therefore, the speed of the projectile and the corpse at all points of the path must be equal, therefore the body of the dog emitted from the projectile continued to follow him, not behind.

But this thought novelist: if the corpse of the dog falls to the Ground, being outside of the projectile, then why would he fall, while inside it? After all, there are the same strength! The dog's body, placed without the support of the projectile must remain hanging in space, it has exactly the same speed as the projectile, and means, in relation to it remains alone. What is true for the corpse of a dog, it is true for bodies of passengers and in General for all objects inside the shell: at each point of the journey they have the same speed as the projectile, and, therefore, must not fall, even if left without support. Chair, standing on the floor of a flying projectile, you can put the legs up at the ceiling, and he will not fall down, because it will continue to rush forward together with the ceiling. The passenger can sit upside down on this chair and stay there, without the slightest desire to fall PA floor of the projectile. What force could cause him to fall? If he fell, i.e., closer to the floor, it would mean, in fact, that the projectile hurtling in space with greater speed than the passenger (or the chair would be closer to the floor). Meanwhile, it is impossible: we know that all objects inside the projectile have the same acceleration as the projectile.

This novelist is not noticed: he thought that the subject freely inside the rushing of the projectile under the influence of mere force of attraction will continue to put pressure on their support, as pressed when the shell was fixed. Jules Verne had overlooked that if the body and bearing moving in space with the same acceleration reported by the forces of attraction (other external forces, the thrust force, the force of air resistance is absent), then push each other they can't.

So from that moment of the journey, when the projectile has ceased to act gases, passengers had no weight and was able to hover in the air inside the shell; similarly, all the items in it should feel completely weightless. On this basis, passengers could easily determine race whether they are in space or still continue to stay in the gun. Meanwhile, the novelist tells how in the first half hour of his heavenly journey passengers in vain puzzled over the question: to fly or not?

“ - Nicole, are we?

Nicole and Ardan looked at each other: they could not feel the vibrations of the bullet.

- Really! Are we? "said Ardan.

Or quietly lying on the ground in Florida? "asked Nicole.

Or at the bottom of the Gulf of Mexico? "added Michel.

Such doubts may have passengers of the ship, but unthinkable passengers freely rushing projectile: first maintained their weight, while the latter can't help but notice that he had become completely weightless.

A strange phenomenon was supposed to represent this fantastic car-shell! Tiny world where bodies are deprived of weight where released from the hands, so they just remain at the place where the items keep balance in any position where the water comes from an overturned bottle... All of this was overlooked by the author of “the Journey of the moon”, and yet how much leeway could give fantasy novelist these amazing opportunities!

Entertaining physics J. Perelman


System Orphus


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