[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 38
You are missing trading opportunities:
- Free trading apps
- Over 8,000 signals for copying
- Economic news for exploring financial markets
Registration
Log in
You agree to website policy and terms of use
If you do not have an account, please register
Planes (don't know about you) can't fly at zero speed relative to the ground (the air is stationary).
And helicopters ?
It doesn't matter what pushes it, the turbine or the wheel itself, it doesn't matter at all.
If it doesn't matter, why don't you fly, Seryoga?
Farnsworth wrote >>.
Yuri, it's elementary.
I liked that one especially.
It's elementary, Watson !
:-)
According to the problem, the barrel is under critical pressure as long as the bubble is at the bottom of the barrel. Any increase in pressure by an infinitesimal amount will cause the barrel to collapse.
Question: will the pressure increase in the system when going from one state (ball at the bottom) to another state (ball) at the top?
Then it will result at the moment of surfacing due to the expulsive force (Archimedean)
Farnsworth писал(а) >> Это было бы так, если бы он уже был бы в воздухе. Это было бы так, если бы вместо шасси была бы воздушная подушка. Но лента-шасси-самолет, - одна система. И пока самолет на земле, - все совсем не так :о)
You love paradoxes, Sergei!
You are sitting in an aeroplane (change the frame of reference). To you (the plane) the picture now looks different - someone is spinning the wheels on the plane. So what of it? That's right - nothing. You will not feel it.
There is another way to think about it. We have to take into account the law of conservation of energy. Is the plane wasting energy by staying in place? - It does! - The turbines work, the gasoline burns. But the plane stands still! A paradox. Where does the energy go? That's right - nowhere. So it can't be like that in principle and our premise is wrong. So the plane must be moving relative to the ground.
According to the problem, the barrel is under critical pressure as long as the bubble is at the bottom of the barrel. Any increase in pressure by an infinitesimal amount will cause the barrel to collapse.
Question: will there be an increase in pressure in the system when going from one state (the ball at the bottom) to another (the ball at the top)?
That turns out to be the problem.
It would have been if it had already been in the air. It would have been if there had been an air cushion instead of a landing gear. But belt-chassis-airplane is one system. And while the plane is on the ground - it's not like that at all :o)
It's an incorrect problem. It depends on friction.
If you reformulate the problem as follows: the plane has no landing gear but skis. It will not take off if the friction force exceeds the pulling force, and it will take off if it has no traction.
With the wheel, it depends on the friction in the bearings and the rubber with the escalator.
According to the problem, the barrel is under critical pressure as long as the bubble is at the bottom of the barrel. Any increase in pressure by an infinitesimal amount will cause the barrel to collapse.
Question: will there be an increase in pressure in the system when going from one state (the ball at the bottom) to another (the ball at the top)?
Actually, presumably it will explode.
When the bubble is at the bottom, it is under the pressure exerted by the barrel, plus the pressure of the liquid column in the barrel.
When it floats to the top, there is no pressure from the liquid column. Reducing the pressure on the bubble should cause it to increase in volume. However, this is not possible under the conditions of the problem: the liquid is incompressible and the barrel does not expand. Therefore, the pressure on the bubble must remain unchanged. This can only happen if the amount of pressure of the liquid column is now provided by the barrel itself. The barrel presses on the bubble, the bubble presses on the barrel. AND BANG! No barrel, no champagne, all wet and foamy. No fun.
Путаете самолёт с трамваем, образно говоря. Посадите птицу на беговую дорожку. Взлетит? Да.
Детский вертолёт с беговой дорожки взлетит? Да.
If the bird flies "upright", yes, it will fly. And a baby helicopter will take off. And a large helicopter will take off - no one is stopping them from doing it. But for aeroplane to take off, it needs to have lifting force on wing, wing has to move with certain speed, and minimal speed relative to the air (if we consider that it is stationary, it means relative to the ground). And the plane will be standing still and humming. It doesn't matter what pushes the aeroplane in this case (even though the pilot sprawls with his legs :o)). You can put a glider and pull it with a winch under these conditions - doesn't matter - it won't take off, either of them.
PS: the glider is not a good example - it will all break.
Neutron wrote >>
By the terms of the problem, the barrel is under critical pressure as long as the bubble is at the bottom of the barrel. Any increase in pressure by an infinitesimal amount will cause the barrel to collapse.
Question: will there be an increase in pressure in the system when going from one state (ball at the bottom) to another (ball at the top)?
-
The bubble floats up because the pressure in the bubble drops as it floats up and the size of the bubble increases. The pressure in the barrel thus slightly
and the barrel doesn't explode.
тогда приведет в момент всплытия за счет выталкиающей силы (Архимедова)
And that's right!
Indeed, the pressure at the bottom of the barrel while the ball is there is P0 and it is equal to the critical pressure for the barrel. The pressure at the top lid is P0-dP and it is less by the pressure of the water column of the liquid in the barrel. By the condition of the problem, the liquid is not compressible and the barrel is not deformable, which means that when it moves upwards, the volume of the ball will not change, so the pressure in it will not change either! Recall that it was equal to P0 and now it is exactly the same at the top lid and at the bottom by dP more, i.e. P0+dP that exceeds the strength limit of the barrel and it will successfully explode.
Вообще-то, повидимому взорвется.
You beat me to it!