Pure maths, physics, logic (braingames.ru): non-trade-related brain games - page 139

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I think a normal room heater is more suitable. Here, all the heat generated can be considered as used. Both convective and radiant heat.
 
muallch: It seems to me that a conventional room heater-heater is more appropriate. Here, all the heat emitted can be considered as used. Both convective and radiant heat.

Makes sense too. I'm prepared to admit that my choices are wrong.

But the general direction still remains: it's only heater-heaters.

And where in the heater-heater does that tiny fraction of a percent come from? What kind of energy is that?

 
Probably losses in wires that have a non-zero resistance.
 
muallch: Probably losses in wires that have a non-zero resistance.
Well, they are still thermal, i.e. useful...
 
Right. Still, in such a device generating the lowest "grade" of energy, it's hard to assume any other energy leakage. E-M radiation (50 Hz and harmonics)? )))). Well, some of the wiring does go outside the heated room as well. Maybe so.
 
Task (5): Divide infinity by infinity.
 
DmitriyN: Problem (5): divide infinity by infinity.

Bad problem, the indeterminacy remains.

Give a concrete example, infinity/infinity doesn't work. If you know how to take integrals/derivatives, no problem. For example, Lopital's rule. Or you don't know it?

 

(4) While looking at the relief map of Brainland, Megamozg suddenly noticed an interesting feature: the average height of any four points lying in the vertices of one square is zero. Is it true that Brainiac is perfectly flat?

Comment: no considerations of relief continuity apply. Brainiac may well turn out to be extremely rugged in height - like a Dirichlet function, for example (this function is not continuous at any point).

The country is known to have no boundaries.

(4) Mega-brain biologist has a 10 cm long stick, on which he puts ants and observes them. The ants can only run along it along its length (left or right); when they reach the end, they fall down. When two ants collide, they both immediately turn around and run in opposite directions. The stick is narrow and ants cannot go around each other without colliding. The ant's speed is 1 cm per second, the ants are moving all the time. After what minimum time is the stick guaranteed to be without ants? The initial number of ants, their positions and directions of movement can be any. The length of an ant can be neglected (consider it equal to zero).

 
moby_dick: Then solve a real problem: Name areal household appliance that has an efficiency factor of 100% to 5 decimal places...
An extension cord ?
 
Mathemat:

(4) While looking at the relief map of Brainland, Megamozg suddenly noticed an interesting feature: the average height of any four points lying in the vertices of one square is zero. Is it true that Brainiac is perfectly flat?

If we represent a contiguous set of squares N x N (N>1), then, apparently, we should prove that in such a matrix the condition of the problem (with respect to all the squares formed) is satisfied only when Brainiac is flat?
1...132133134135136137138139140141142143144145146...229
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