[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 137
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How about heat?
Here's a simple problem:
Two identical vessels are put on two identical burners at the same time. One has 1l, (N1) the other has 0.5l (N2) of water of the same temperature. At the moment the half-litre boils, another half-litre of water of the original (preheating) temperature is poured in there. The burners are put out. In which vessel will the temperature be higher?
1. Let the initial temperature of the water in the vessels be 20g C.
2. The water in the 0.5l vessel will be heated by 80 deg C i.e. to 100g C.
The water in the 1l vessel will be heated by the same amount of energy by 40g.C i.e. to 60g.C.
3. Pour 0.5 l of water with a temperature of 20 g.C. into both vessels.
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The temperature in the 0.5 l vessel was (0.5*100+0.5*20)/1=60gr.C.
In 1l vessel the temperature was (0.5*20+1*60)/1.5=35gr.C.
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PS:
1. the heat capacity, mass and temperature of the vessels have been neglected.
2. the change in the heat capacity of water and vessels has been neglected.
3. the change in the heating efficiency (depends on the shape of the vessels) has been neglected.
4. evaporation has been neglected.
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The conclusion is that the temperature is higher in the 0.5-liter vessel.
Read the problem statement more carefully. Half a litre was only poured into a 0.5 litre vessel to equalise the masses. The point of the problem is to understand how to heat more efficiently: all at once the whole mass or in parts.
As for the brick, which is still flying, you probably meant that it will either a) swell and stick, or b) melt and smear on the walls from the high temperature. :-)
Read the problem statement more carefully. Half a litre was only poured into a 0.5 litre container to equalise the masses.
........ At the moment the half-litre was boiling, so much more was poured in..........
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Which way is that? >> Where is there?
........В момент закипания поллитра туда залили еще столько..........
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Куда туда? Туда - это где?
In the kitchen.
In the pot where the phone used to lie, which was put by your mother-in-law, who was in the kitchen, where you only go to eat
How can the condition "Two identical vessels" be interpreted differently, one of which holds a litre
Может, про тепло?
Вот простенькая задачка:
Два одинаковых сосуда ставят одновременно на две одинаковых горелки. В одном 1л, (N1) в другом 0,5л (N2) воды одинаковой температуры. В момент закипания поллитра туда залили еще столько же воды с первоначальной (до нагрева) температурой. Горелки гасят. В каком сосуде т-ра будет больше?
It's kind of the same.
What's the joke?
Mathemat писал(а) >> Прикол в том, что кое-что меня и тут смущает. Почему "орел-решка" (ОР) и "решка-орел" (РО) считаются как разные исходы?
Well... I just think so; I don't know any other arguments yet :)
I mean, why not: 1/3*2 (two tails) + 1/3*1 (heads and tails) + 1/3*0.5 (two eagles with half of tails) = 7/6?
Patamushta the coins can be distinguished from each other. Distinguishable = boson-fermion theme. You're ripe for that?
;-)
Ну вроде одинаково
В чём прикол ?
Yeah, it depends on what else to neglect :-))ага, это в зависимости чем еще пренебречь :-))
That's right. A bureaucratic suggestion: let the authors attach an IgnoreList to each task - "a list of related idealisations". That'll make life a lot easier. :)
........The moment half a litre boiled, they poured so much more in there..........
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Which way is that? Where's there?
That's in the half-litre. In the middle. Nobody touched the litre.
Question for you
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A gas cutter used 20 litres of propane gas to cut 20 cm of 5 cm thick steel with a propane-oxygen torch.
Is it possible that he will not use more than 40 litres of propane gas to cut 2,000 cm of the same 5 cm thick steel.
If so, how is that possible?
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