The Mpemba Effect and why hot water freezes faster than cold

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The Weather Network

Күн бұрын

Пікірлер: 63

@vinnyeggers5493 5 жыл бұрын

The title of this vid lead me to believe I would get an actual answer to the question posed....

@ManifoldSky 11 ай бұрын

You won’t get an answer because the effect is not real

@buzzbuzz10 3 жыл бұрын

It's an age-old question with a simple answer: no. When the temperature of the water in each container reaches just about 0°C it will undergo the same changes as it moves from a liquid to a solid, and it will take the same amount of time to begin forming tiny ice crystals. Different set ups will have different results due to extraneous factors not effectively altering the basic proposition.

@vincentrobinette1507 6 жыл бұрын

Hot water atomizes better, exposing more surface area for the amount of mass. More surface area, more rapid heat transfer. Hot water has a higher vaporization pressure, thus finer mist. If you take two identical glasses of water and put them on the side walk, the cold one will freeze faster. The warm water will transition down to the temperature of the cold glass, and from that point, it will freeze at the same rate. It takes time for the hot water to get down to the temperature of the cold water, but not long. There is a bigger temperature difference when hot, thus heat transfer is more rapid. You have to throw it, to take advantage of extra surface area. Mpemba effect does NOT apply to still water in a vessel.

@riosalbei 5 жыл бұрын

yes it does. please inform your self better: en.wikipedia.org/wiki/Mpemba_effect

@willemmkuipers 4 жыл бұрын

It's actually the other way around. Your explanation is completely correct, but the internet still believes the phenomenon filmed, is the Mpemba effect. That is nonsense, since Mpemba applies to a vessel of warm water, over a longer period of time (half an hour). You're correct that the much lower viscosity of hot water is the reason it atomizes better

@Mike-sp2eu 3 жыл бұрын

@@riosalbei did even read it yourself? Look under modern experimental work,... They noted that the large difference originally claimed had not been replicated, and that studies showing a small effect could be influenced by variations in the positioning of thermometers. They say, "We conclude, somewhat sadly, that there is no evidence to support meaningful observations of the Mpemba effect. . Please inform yourself better before commenting

@pianoraves 4 жыл бұрын

The boiling pot is avery different setup from the experiment where the Mpemba effect is classically observed. As far as I can tell, the reason why the water freezes here is that boiling water easily atomizes if you throw it into the air, which means it has a much greater surface area that lets it freeze almost instantly.

@rabidpogoista4510 4 жыл бұрын

Yes, but the point is that you have to do it with boiling water. It doesn't work if you do it with cold water. So while this isn't the typical setup used to observe the Mpemba Effect, it is nonetheless the Mpemba Effect at work.

@pianoraves 4 жыл бұрын

@@rabidpogoista4510 I didn't deny that

@ManifoldSky 11 ай бұрын

@@rabidpogoista4510No it’s not

@miriammhando748 4 жыл бұрын

He is still alive here in Dar Es Salaam

@cuchelo1 3 жыл бұрын

After years of seeing videos of ppl doing this, I finally found myself in an area cold enough to try- and it worked! I'm happy enough with my video of "creating snow", lol...

@bossybill7437 2 жыл бұрын

Here an experiment to show the cause of the Mpemba Effect... For the Control (this one will show the Mpemba Effect)... Two beakers, one with 'hot' water the other with cool water. Both fitted with external thermometers for monitoring outside the freezer. Place both in the freezer and monitor for when each freezes. If done correctly, the the Mpemba Effect will result in the 'hot' beaker freezing first (and this will establish a baseline from with the Effect can be reliably repeated). THIS following test will show the cause of the Effect... repeat above procedure BUT... Monitor the temperatures and when both beakers reach the same temperature, _stir the contents of both_ then continue freezing. The prediction is that both beakers will then go on to freeze at the same time. This shows that the Mpemba Effect is produced by the inertia (ie. momentum) set up within the convectional currents within the beakers. When the temperatures of both beakers become equal and inertia of the convectional currents is equated across the beakers (by stirring both of them), the Effect disappears. This shows that the Mpemba Effect is a result of the stronger convectional current established in the hotter liquid (due to its greater thermal difference in the beaker's column gradient, compared to the cooler liquid). The stronger convectional current facilitates more rapid cooling on the beaker's surface because it is flowing across the beaker's surface faster (because the current is stronger, because the temperature gradients (top to bottom) are greater. Rate of energy transfer is influenced by the difference in temperatures. Energy transfer, from the beaker to the freezer will be faster in the beaker with the 'hot' water (greater temperature difference), and this will establish a stronger convectional current that will in turn establish greater inertia (water flow velocity past the beaker surface) within the 'hot' beaker's current. As both beakers pass the point where their temperatures are equal, the 'hot' beaker will have a faster flowing current. This will then result in the 'hot' beaker reaching a lower temperature (eg. freezing) sooner.

@bossybill7437 2 жыл бұрын

Another view of the Mpemba Effect is to carry out the experiment and consider _what differences exist between the beakers, during the cooling, when their temperatures become equal._ _Obviously,_ the only difference during cooling, at the point when their temperatures are equal, is the strength of their convectional currents. Prove this by stirring them _then_ (or in other words, reset or equalize, their convectional currents), and they will then continue cooling at the same rate and subsequently freeze at the same time.

@baneverything5580 2 жыл бұрын

Hot water also contains less air.

@ManifoldSky 11 ай бұрын

@@bossybill7437Those are NOT the only differences

@bossybill7437 11 ай бұрын

@@ManifoldSky As I said above... "Prove this by stirring them then (or in other words, reset or equalize, their convectional currents), and they will then continue cooling at the same rate and subsequently freeze at the same time." But yes, there are inevitably a number of other differences (for example, their exact positioning and subsequently, different exposure to draft air currents), but I would assert these 'other' differences are minor, controlled for minimisation, and beside the point.

@ManifoldSky 11 ай бұрын

@@bossybill7437 And AGAIN, those are NOT the only differences. Numerous empirical experiments that have disproved there supposed Mpemba Effect Have shown that even small microscopic imperfections and differences in glassware that serve as crystallization seed sites have a huge effect on final freezing point. Stirring has little to nothing to do with it.

@Watts378 3 жыл бұрын

Wow she's gorgeous!! I didn't learn a thing.

@billywillgo69 5 жыл бұрын

The Mpemba paradox is the result of the unique properties of the different bonds that hold water together, and how those bonds are changed when hot or cold and how the changes are the reasons one (hot) can cool faster than the other (cold).

@neilmekolichick6582 3 жыл бұрын

The guy at the end gets the boiling hot water bucket challenge

@CatherineKayeyyc 8 жыл бұрын

It's a phenomenon. "Phenomena" is the plural of "phenomenon".

@pianoraves 4 жыл бұрын

They're phonetically very similar, especially in the USA

@clems6989 2 жыл бұрын

None of the proposed explanations involve sealed pipes..

@filiplinhart9034 4 жыл бұрын

I tried several times in my freezer, but nothing spectacular, the hot water freezes at the same time as cold water, yes, but not before.

@ManifoldSky 11 ай бұрын

If they froze at the same time, that same would demonstrate the effects. But they DON’T.

@pokemongomaster5798 6 жыл бұрын

the real reason is boiling water structures it to the shape it freezes better in

@darkcookie4830 4 жыл бұрын

Good that you just know the answer to a question scientists are working on for years. Why did you keep your secret from the World?

@bossybill7437 2 жыл бұрын

@@darkcookie4830 Some guys in Nanyang University postulated it's something to do with hydrogen bonds. I think it's simply a function of the stronger convectional current set up in the hotter water. Why they're taking so long to figure this, is the real mystery. Here... consider freezing a hot beaker and cool beaker. When the temperatures of both are the same (ie. just as the hot overtakes the cool, but before either freezes)... What is the difference between the beakers? Nothing... they're both at the same temperature _EXCEPT_ the hot beaker has established a stronger/faster flowing convectional current (it will have more inertia, then the other, to continue flowing faster). That stronger current will have a greater cooling effect (because it's flowing faster, like turning a fan on High verses Low). Therefore the hot beaker will continue on and freeze before the cool beaker.

@Mike-sp2eu 3 жыл бұрын

The hot water didn't freeze and she even admitted to it,. What a contradiction

@quentinbradford8127 5 жыл бұрын

Anyone else here ever heard of a country called Tanzanania??? Apparently the guy who discovered this was a "Tanzananian". HUH??? 0:31

@emzyvan4152 5 жыл бұрын

Quentin Bradford well the country is Tanzania, the guy was Tanzanian as in, from Tanzania

@quentinbradford8127 5 жыл бұрын

@@emzyvan4152 My comment obviously went so far over your head it may as well have been in orbit. You obviously didn't pay any attention to the horrible narration, did you?

@solomon9853 4 жыл бұрын

It's a country in Africa

@pianoraves 4 жыл бұрын

@@quentinbradford8127 your comment went so far over his head it was outside the soi

@fighterm7708 2 жыл бұрын

Yes it's our Country Tanzania located East Africa .include Zanzibar Islands ( unguja and Pemba ). Also with Ngorongoro and highest Kilimanjaro Mountain.