Pure maths, physics, logic (braingames.ru): non-trade-related brain games - page 97

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alsu:
Yeah. If you put a battery in front of the wires, and screw it on, it'll turn on too.
There's no need for a battery. The fan generates its own current. And you don't need four magnets, you only need one. It affects the reed switch, shorting the ends of the fan. The reed switch is under the duct tape. The man is just fooling people with his magnets.
 
alsu:
I think it's only in modern Russia that they would put electronic circuits in case fans)) Bourgeois consider well and design mold the simplest, otherwise the fan would not be worth 100 rubles. This is why computer fans only use cheap brushless DC motors, which produce much less electromagnetic interference than asynchronous motors.

According to the information on the internet, the coolers have both a hall sensor and a chip. A chip is not a problem, an electronic wristwatch costs a few roubles. If there is no Hall sensor, it's not an asynchronous motor, it's a synchronous motor:)

 
Integer:

According to the information on the internet, the coolers have both a hall sensor and a chip. A chip is not a problem, an electronic wristwatch costs a few roubles. If there is no Hall sensor, it won't be an asynchronous motor, but a synchronous one:)

If it's correct, it's synchronous. But, there is a hall sensor. But, the thing is, that's where the electricity is generated - that's the twist.
 
DmitriyN:
If it's correct, it's synchronous. But, there is a hall sensor. But, the thing is, it generates electricity - that's the beauty of it.

It doesn't generate electricity and we are just discussing how the motor in the cooler is designed.

 
TheXpert:

No, that's not all. We still have to prove that (1) is also true for the geometric centre at the centre of the circle, well, and prove that the run to the points is at least not closer than the geometric centre.

In this case there is a specification that one cannot shove all the flags to the same point.

Yep.

alsu:
Yes, we do. Later
Exactly, and the proof is based on the simplest fact known to all.
 
Mathemat:

Yep.

Exactly.
Volodya's already made up his mind
 
Integer:

Microcircuit

I don't think it's so much a "micro" as a "circuit" on a printed circuit board.)
 
alsu:
Volodya has already made his point.

OK, here's my shamanism (credited):

A: MM will always be able to escape.

Rationale: MM acts as follows: first he calculates the "centre of gravity" (CG) of the flags by a well-known formula in physics, assuming that the flags' masses are equal. Then as the case may be:

1. If the center of gravity does not coincide with the centre of the circle O, then MM chooses a point on the circle as far away from the center as possible. It is sufficient to draw a line passing through the CT and the centre of the circle, and choose from the two points of the circle.

2. If the CT coincides with the point O (which is most likely what the occupants will do), then Megabrain will have a harder time - but not by much.

The set of checkboxes is viewed as extended from at least one point, since the set is not a mathematical point according to the problem. In other words, even if all flags are arranged in a line, MM can always find a point on the circle from which this line will be visible at a non-zero angle (not all directions of view on flags are collinear).

This is the point he points to. To be sure, he tries to find a point on the circle from which the whole set of flags is visible at the maximum angle.

All reasoning is based on the following fact: A vector length equal to the sum of vectors emanating from one point is not greater than the sum of vector lengths. The only exception - exact equality - holds when all vectors are collinear.

This fact is a simple consequence of triangle inequality in ordinary Cartesian space.

Since, in the second case, the CT is distant from MM at a distance equal to the radius of the circle, then, according to the above fact, the distance the runner must run is greater than the 60 * radius of the circle = 6000 m, which he will run for over 10 minutes.
 
alsu:
I don't think it's so much "micro" as it is a "circuit" on a printed circuit board.)

I don't know if it's been a long time since you've broken into modern technology; everywhere you go, there's a chip, not necessarily in a casing, but more often a millipede in a drop. Even Christmas tree garlands have such a thing. It's as if they make microchips for every occasion.

 
alsu:
I don't think it's so much "micro" as it is a "circuit" on a circuit board.)
OK, forget it. Maths is here, physics is over, maths is coming up. When I have time I'll buy a fan and make the same thing, the fan will spin itself, I'll take a video and post it.
I used to have a fan like that, given to me by my dad, but I got to the bottom of it and broke it, it doesn't spin anymore - it's burnt out.
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