[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 33
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То есть ты думаешь, что если я залезу в этот самолет с сильным вентилятором и включу его, то возрастет давление на все стенки, и при том одинаково ? Так это же кладезь, так можно вечный двигатель сделать. Тогда и форес не нужен. И человечеству будет польза. Большая. :-)
That's a great example. Munchausen is also a good example.
Speaking of wheels. Tyres get a lot of abrasion when a plane lands. To reduce this wear, there's an invention - an electric motor in the landing gear. It spins the wheels of the landing gear to a circular speed equal to the speed of the flight and contact with the runway surface occurs without sliding and wear on the tyres.
What about the plane? It's jet-propelled, held up by the wings on a wave of air due to the difference in pressure from below and above the wing. Reactive force pushes the plane forward. The speed of the aeroplane depends on the reactive force and on the lift force. Neither the speed of the ground, the direction of rotation of the ground, nor the distance from the ground determine these factors. Therefore, the plane will take off. It's just that its wheels will be spinning at twice the speed during take-off. That's all there is to it.
That's all except for the wheels. They won't be spinning at all.
I'll try my question again, in case the opposition answers :o)
I wonder if we were to open the door, in a fly buzzing plane - what would happen to the weight? Would it drop by a tonne??????
Все так, кроме колес. Они вообще не будут крутиться.
Yeah and the plane will be standing still (and relative to the ground). That's all there is to it. Of course it will. :о))))
I'll try my question again, in case the opposition answers: :o)
I wonder if we were to open the door, in a fly buzzing aeroplane - what would become of the weight? Would it drop by a tonne??????
Yes, the average air density would decrease and the weight would drop. But, just a ton of flies I find it hard to imagine in an aeroplane.
Попробую свой вопрос повторит, вдруг ответит оппозиция: :о)
Интересно, а если бы мы открыли дверь, в жжужащими мухами самолете, - что стало бы с весом? Неужели упал бы на тонну??????
The flies would have fallen or pri-per-fallen. It would just make it that much harder for them to create a 1 tonne cushion of air. Can a hovercraft fly? No. Why not? Because as it rises above the ground its cushion of air, according to Blaise Pascal's law, diverges sideways and it falls to the point where the difference in pressures above and below balances its weight.
Farnsworth, Imagine that the pressure in the plane was 2 kg/cm². You opened the door and the pressure dropped by half. Half of the air is out. The mass of the plane and its weight will decrease.
А что самолёт? Он реактивный, держится крыльями на волне воздуха за счёт разницы давлений снизу и сверху крыла. Реактивная сила толкает самолёт вперёд. Скорость самолёта зависит от реактивной силы и от подъёмной силы. Ни от скорости земли, ни от направления вращения земли, ни от расстояния от земли эти факторы не зависят. Поэтому самолёт ВЗЛЕТИТ. Просто колёса его будут во время взлёта крутиться с удвоенной скоростью. Делов-то.
Quite right. The aeroplane's engines give it speed relative to the air around it. When the speed is high enough for the lifting force to exceed its weight, it will take off, i.e. it will start climbing upwards. Even, a situation may arise where it will be stationary horizontally relative to the ground if the air mass moves with sufficient velocity towards it, without, of course, the wheels turning at all.
ZS in a wind tunnel, a sports car can be stationary on the ceiling.