[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 237
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Perpetuum Mobile oblige. Take a healthy threaded pin and place an even healthier disc with the appropriate internal thread on it and release. The disc starts to descend by rotating. Because of the relativistic effect, we will get more energy at the end than for lifting the disc up.
I don't understand who is covering the dog here. The maximally informative answer from the physicist is, "No, well, that's something else!"
Could it be something about the coordinate system or something else?
Perpetuum Mobile oblige. Take a healthy threaded pin and place an even healthier disc with the appropriate internal thread on it and release. The disc starts to descend by rotating. Because of the relativistic effect, we will get more energy at the end than for lifting the disc up.
I don't understand who is covering the dog here. The maximally informative answer from the physicist is, "No, well, that's something else!"
Could it be something to do with the coordinate system or something else?
Imya, what do you mean more? Most of the energy in general will go to thread friction, and what percentage depends on the pitch of the thread, the smaller it is, the more. And what does the RE have to do with it, that's a misconception.
Richie, there you go again with your practical arguments. Forget about friction, there is none. The disc is very large and heavy.
Once again we are faced with the mathematical shortcomings of programming languages :) I once solved this problem in VB by creating my own type:
' Declare three variables with possible values from -1E1000 to 1E1000 and up to 5000 decimal places
Dim x1, x2, x3 As Double(-1E1000, 1E1000, 5000)
Who prevents language creators from doing this?
Good for you, Richie! Have you ever thought about how many resources such numbers will eat up in the calculations?
Richie, there you go again with your practical arguments. Forget about friction, there is none. The disc is very large and heavy.
All right, so there's no friction. Where's the energy coming from? RE is an interesting thing, but a lot of people get it wrong.
Well done, Richie! Have you ever thought about how many resources such numbers will eat up in the calculations?
Yes, a lot, the computer hangs. But, sometimes you really need to count something very precisely :)
By the way, you can limit the range, for example for Double or Long, and then you'll need less memory and the computer will count faster.
Not using range completely will throw out a lot of memory.
Well, roughly speaking, because, say, the outer regions of the disk will rotate with very high speed relative to any inertial reference system - and will have a different "mass".
Well, that's a two-way street. There is also a change of scale.
P.S. About accuracy: in astronomical calculations, accuracy is of the order of tens of decimal places. But not thousands. This accuracy is justified only by the need to work with large integers. What do you need such integers for?
Where do you want these in one piece?
This is purely for theory. In life, I've never used more than 15 digits, and in practice even less - five digits.
Ну хорошо, пусть трения нет. Откуда энергии больше? РЭ конечно вещь интересная, но многие его понимают не верно.
That's what I want to understand it 'right'.