[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 109
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And the condition says that the speed of the conveyor belt is equal to the speed (circumferential or whatever you want to call it) of the wheels. And it doesn't matter if the engine is on, off or what is rubbing against the ground. If this condition is met, it means that the plane is stationary relative to the ground. If the plane is moving apart (and therefore moves relative to the ground), then the speed of wheels is greater than the speed of the conveyor belt, which is contrary to the condition. So, either reduce thrust, or it will be a totally different problem. And in this one, no one is flying anywhere.
I knew it ... :-(
This (highlighted in bold) is indeed a gaffe and incorrect. But you ate it and you shouldn't have. So now you have indigestion and that makes you think the plane is stationary relative to the ground.
This has already been said, but I will repeat: if there is no wheel slippage on the transporter (and everyone agrees on this), then the linear (or circumferential) speed of the wheel rim relative to the transporter is zero, and therefore the transporter speed and the linear speed of the wheel are always equal! This could have been omitted from the problem statement. And it was implied that the velocity of the transporter is equal in magnitude and opposite in sign to the velocity of the plane, not the wheel. Both velocities are, of course, relative to the ground.
Given this correction, what would be your verdict ?
OK! What's the turkey?
However... that could get you banned in this thread... ;)
There's an idea to make a "good" wrecker. For fun. Let's see what happens.
Yes, Mathemat, your intuition told you one thing and life told you another, so you haven't solved the fly-in-the-plane issue, while it told you the right thing, and you listened to people like me :)))
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Anyway, I'll answer that myself. In part. By flies I mean small particles, not flies - in the biological sense of the word.
"Flies" can indeed do something that causes a vessel to take off and fly for a very long time, expending a small amount of energy to do so. But, that's what? It does not contradict physics, but not everyone can come up with it, precisely because some of the stereotypes of our popular education get in the way.
Ну так про тот даже Farnsworth согласился, что он взлетит, правда только при условии, что будет с мухами.
Но если физика вообще не при делах, то огласить правильный ответ просто необходимо.
You still can't settle down and you're a bit of a liar. You haven't seen that before, which is a pity. That's not what this task is about and it's a pity you can't see it. When the argument reached its climax, I wondered what was going on. Once again I looked at statistics, like this (it's typical for this problem with slight differences in percentage):
Is it that so many people in such a proportion know or do not know the answer - it can not be, especially since the task is mostly discussed in technical forums and people are not stupid. Then I carefully looked at the conditions and realized that both those who say it will take off and those who say it will not. And objectively, those who say that the problem is not correct are right. I don't understand why you think it's correct. The purpose of the problem is different, - to create flame, but it's not easy to do if the participants will have the same understanding of the conditions. And the author of the task - it worked, you can measure the number of posts.
It was a little bit unexpected to see your reaction, Sergei, Vladislav, where, for example, he was taught to equate quantities with different units so easily and simply, I don't know. Maybe you need a break, maybe to trade, to increase the deposit. I'm starting to worry about your brain. It might burst and stain your surroundings.
Yuri, I can not stand showing off, and even more so on a level playing field with such a sick ego and conceit. Therefore, I won't bother you. Enjoy it.
Я так и знал ... :-(
Это (выделенное жирным) действительно ляпсус и некорректность. Но вы ее съели, а не надо было. Вот теперь у вас несварение и от того вы думаете, что самолет неподвижен относительно земли.
Это уже говорилось, но я повторю: если нет проскальзывания колес на транспортере (а с этим все согласны), то линейная (или окружеая) скорость обода колеса относительно транспортера равна нулю, и потому скорость транспортера и линейная скорость колеса равны всегда ! Это в условии задачи можно было не задавать. А подразумевалось, что скорость транспортера равна по величине и противоположна по знаку скорости самолета, а не колеса. Обе скорости, понятное дело, относительно земли.
С учетом этой поправки, каков будет ваш вердикт ?
It is relatively clear there :)
Problem about an aeroplane on a transporter: An aeroplane (jet or propeller) stands on a runway with a movable covering (like a transporter). The runway can move against the plane's take-off direction, i.e. towards it. It has a control system that monitors and adjusts the speed of the runway so that the speed of the wheels of the aircraft is equal to the speed of the runway.
What to measure and relative to what is not prescribed. But! The speed of the web has to be "adjusted to the speed of the wheels". So it's not referring to their mutual speed - it's really zero, there's nothing to adjust. And not relative to the plane - it's in the "unknowns".
The speed of the wheels is compared to a linear speed - so you have to make it linear. Relative to what? Relative to the axle. Not the web - we've already decided above that it is 0. And not the ground (in the unknowns, together with the web/plane).
And these are consistent and self-sufficient assumptions, and by that they are better, and therefore more correct, than other assumptions.
TASK #11:
A flying saucer with a mass of 10,000 tons is hovering motionless in the air.
Question: What is the theoretical minimum power of the saucer's engine to make it hover like this?
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PS: The acceleration of free fall at the hovering place is 9.81 m/sec. Wind, friction, efficiency are not considered.
Да, Mathemat, интуиция вам подсказывала одно, а жизнь другое, так вы и не решили данный вопрос с мухами в самолёте
I still think the plane will be a ton lighter when they all take off (the plane is on the scale).
Now, this is where I don't give a damn about life and experience: this thread is not about solving life's problems, it's about twisting the ability to solve non-standard problems that require straining the brain rather than experience. That's what the branch is for.
Slightly more than zero. Firstly, because they are both attracted to the centre of the Earth (there is already an angle between the vectors), and secondly, because they are also attracted to each other. But the attraction to each other can be neglected.
Чуть больше нуля. Во-первых, потому, что они оба притягиваются к центру Земли (между векторами уже есть угол), а, во-вторых, потому, что они еще и друг к другу тянутся. Но притяжением друг к другу можно пренебречь.
It's understandable, but where's the gimmick, there must be something wrong.
Richie's tasks have a lot in common,
I'm gonna guess the answer is 0.