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Topic: Mpemba effect

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	Mpemba effect - Wikipedia, the free encyclopedia
		The Mpemba effect is the observation that, in some specific circumstances, hotter water freezes faster than colder water.
		Mpemba first encountered the phenomenon in the classroom of Eugene Marschall at Mkwawa Secondary (formerly High) School, Iringa, Tanzania, where Mpemba was a student.
		Mpemba first noticed the effect in 1963 after his account of the freezing of hot ice cream mix in cookery classes, and went on to publish experimental results with Dr. Denis G. Osborne in 1969.
	en.wikipedia.org /wiki/Mpemba_effect (539 words)

	Mpemba effect - Education - Information - Educational Resources - Encyclopedia - Music
		The effect is named for its rediscoverer, the Tanzanian high-school student Erasto B. Mpemba, in 1963 after observing the freezing of ice cream in cookery classes; he published experimental results with Dr. Denis G. Osborne in 1969.
		Mpemba's story is often given as a cautionary parable to those who reject theories or experiments solely because they seem counterintuitive, or contradict accepted theories, or because their proponent is not an expert.
		In the six years between Mpemba's discovery and his publication, his ideas were rejected on a number of occasions by his physics teachers and other authorities, and it was only the reproducibility of the effect by himself and others that drove Mpemba to persist against this resistance.
	education.music.us /M/Mpemba-effect.htm (703 words)

	Mpemba effect (Site not responding. Last check: 2007-10-30)
		The effect was discovered by the Tanzanian high-school student Erasto B. Mpemba in 1963 after observing the freezing of ice cream incookery classes; he published experimental results with Dr. Denis G. Osborne in 1969.
		The effect is not universal under all experimental conditions soits exact requirements have proved difficult to specify.
		The effect was known to ancient and medieval scientists such as Aristotle, Francis Bacon and René Descartes, but modern science had reduced it to folklore.
	www.therfcc.org /mpemba-effect-45116.html (156 words)

	Mpemba-Effekt - Wikipedia
		Mpemba selbst hat eine solche entdeckt, indem er sein Eis schneller gefrieren lassen konnte.
		Diese bestand in Mpembas Fall darin, dass er weniger Speiseeis produziert hat, als unter optimalen Bedingungen möglich gewesen wäre (und er zudem den Kühlschrank öfter enteisen musste).
		Mpembas Verdienst ist es, den Effekt wiederentdeckt und einem breiteren naturwissenschaftlich interessierten Publikum bekannt gemacht zu haben.
	de.wikipedia.org /wiki/Mpemba-Effekt (2409 words)

	Pathological science - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-30)
		The maximum effect that is observed is produced by a causative agent of barely detectable intensity, and the magnitude of the effect is substantially independent of the intensity of the cause.
		The effect is of a magnitude that remains close to the limit of detectability, or many measurements are necessary because of the very low statistical significance of the results.
		The issue is not whether an effect actually exists, nor whether people "believe in it"; the issue is how the support for the claim is given.
	www.sciencedaily.com /encyclopedia/pathological_science (1751 words)

	The Mpemba Effect: Hot Water Freezes before Cold - Succeed in Physical Science
		The Mpemba Effect is a special phenomenon where hot water freezes faster than cold water.
		The discovery of this effect was made by a high school student named Mpemba in Tanzania, Africa in 1969.
		Mpemba was making ice cream when he made his discovery.
	www.school-for-champions.com /science/mpemba.htm (1818 words)

	Mpemba effect - InformationBlast
		The effect was discovered by the Tanzanian high-school student Erasto B. Mpemba in 1963 after observing the freezing of ice cream in cookery classes; he published experimental results with Dr. Denis G. Osborne in 1969.
		At first sight, the effect is contrary to Newton's law of cooling.
		The effect is not universal under all experimental conditions so its exact requirements have proved difficult to specify.
	www.informationblast.com /Mpemba_effect.html (159 words)

	Can hot water freeze faster than cold water?
		While you will often hear confident claims that X is the cause of the Mpemba effect, such claims are usually based on guesswork, or on looking at the evidence in only a few papers and ignoring the rest.
		Subsequent experiments were done with water in a closed container, eliminating the effects of evaporation, and still found that the hot water froze first [14].
		Experiments have been done that looked at the convection currents of freezing water [27,28], but their implications for the Mpemba effect are not entirely clear.
	www.desy.de /user/projects/Physics/General/hot_water.html (4282 words)

	Kennislink - Een huis vol mysteries
		Het is genoemd naar de Tanzaniaanse student Erasto Mpemba, die het in 1969 opmerkte bij het bereiden van roomijs.
		Mpemba ontdekte dat roomijs sneller wordt gevormd als je het mengsel vooraf tot kamertemperatuur verwarmt en dan pas bevriest.
		Later bleek dat het effect al langer bekend is. In de vierde eeuw voor onze jaartelling schreef de Griekse filosoof Aristoteles: "Wanneer water vooraf verwarmd wordt, draagt dat ertoe bij dat het sneller bevriest, want zo koelt het sneller af.
	www.kennislink.nl /web/show?id=93591 (2256 words)

	Encyclopedia :: encyclopedia : Wigner effect (Site not responding. Last check: 2007-10-30)
		The Wigner effect, also known as the discomposition effect, is a change in the physical or chemical properties of a crystalline solid resulting from damage caused by radiation.
		As a result of the Wigner effect, the physical dimensions of the crystalline solid are changed and energy is stored in its structure; this is known as Wigner energy.
		It is a major risk for nuclear reactors that use graphite as a neutron moderator.
	www.hallencyclopedia.com /Wigner_effect (121 words)

	BBC - Gloucestershire Weather - Hot Stuff makes an Ice Surprise!
		The story continues in a Tanzanian high school in 1969 where a schoolboy by the name of Mpemba was making ice cream by mixing boiling water and sugar.
		When Mpemba asked his physics teacher for an explanation he was told he must have been mistaken - his results were impossible.
		Mpemba believed his teacher at the time but less than a year later he met a friend who made and sold ice cream commercially.
	www.bbc.co.uk /gloucestershire/weather/2003/12/ice.shtml (771 words)

	Hot Water Freezes Faster than Cold!
		The effect is definitely real and some people claim to have duplicated it in their refrigerator.
		This question is a favourite of popular science magazines where it is often referred to as the Mpemba effect after a Tanzanian student who observed it while making ice cream and raised the question in 1969.
		To explain the Mpemba effect through convection alone it would be necessary to show that hot and cold water currents are separated in the process and that convection can continue after the average temperature had dropped below 4C.
	hepth.hanyang.ac.kr /~sjs/physics/hot_water.html (1598 words)

	Tonyandpals.com
		A number of experimenters have argued that evaporation alone is insufficient to explain their results [5,9,12] -- in particular, the original experiment by Mpemba and Osborne measured the mass lost to evaporation, and found it substantially less that the amount predicted by Kell's calculations [5,9].
		Indirect support can be found in two experiments that saw the Mpemba effect in normal water which held dissolved gasses, but failed to see it when using degassed water [10,14].
		If true, this could explain the Mpemba effect because the initially cold water would need to "do more work" -- that is, get colder -- in order to freeze.
	www.tonyandpals.com /modules.php?op=modload&name=Forum&file=viewtopic&topic=39420&forum=8&34 (9670 words)

	De Cavia Wereld
		Onwaarschijnlijk: het glas met warm water is sneller bevroren dan het glas met koud water...
		Een high school student genaamd Mpemba in Tanzania, Afrika ontdekte in 1969 dat heet water sneller bevriest dan koud water toen hij ijs aan het maken was.
		Zijn leraren geloofden in het begin niet dat dit mogelijk was en het duurde een paar jaar voordat professors van de universiteit uiteindelijk zijn ontdekking erkenden.
	cavia.skynetblogs.be /?date=20050421&number=1&unit=months (382 words)

	Heat Questions (Site not responding. Last check: 2007-10-30)
		Another scenario suggested for the "hot water freezing" story is the possibility of supercooling and snap-freezing by the hot water.
		There is in fact a large body of literature about initially hot water freezing faster than cold water and this phenomenon has been labeled the "Mpemba effect" (see references).
		The literature cited here takes the position that the phenomenon of supercooling is the main mechanism involved and that the history (dissolved gases, etc.) are not crucial to the phenomenon.
	hyperphysics.phy-astr.gsu.edu /hbase/thermo/freezhot.html (302 words)

	Cooling of liquids
		In effect you start off with two mugs full of similar liquids but one is
		Mpemba was given credit for noticing the issue.
		Is the Mpemba effect now taught in the U.S. Public School System?
	www.groupsrv.com /science/viewtopic.php?t=78433 (918 words)

	…grayblog…- separating the wanted from the unwanted » Cold out. Cold in as
		On the subject of cold things, there was an interesting discussion on the increasingly-irritating Today programme of the Mpemba effect.
		Essentially, as a result of the Mpemba effect, hot water will freeze over more quickly than cool water, even though that would seem to counter logic.
		Practical applications of this are that you should put cold water onto your pond or birdbath if you would like the creatures to benefit from that, and also use cold water to de-ice your car windscreen.
	www.grayblog.co.uk /index.php?p=3450 (155 words)

	WCReplays.com
		It's called the Mpemba effect and it basically says that in some circumstance water that starts out hotter will cool faster that water that begins cooling at a lower initial temperature.
		about the "Mpemba effect" or however u called it: If you take a fixed mass of water(like 1kg) at a specific temperature it WILL take longer to get 1kg of 0°C water if it was at 70° than if it was at 50°.
		The Mpemba effect is the result of the increased speed of evaporation caused by the high temperature difference between the water and the air.
	www.wcreplays.com /articles.php?get=31 (3115 words)

	Learn more about Water in the online encyclopedia. (Site not responding. Last check: 2007-10-30)
		Distilling: Distillation involves boiling the water to produce water vapor.
		However, richer countries such as Kuwait can more easily cope with low water availability.
		Mpemba Effect ~ Can hot water freeze faster than cold water?
	www.onlineencyclopedia.org /w/wa/water.html (1963 words)

	Sixty-three anomalies of water
		Hot water may freeze faster than cold water; the Mpemba effect.
		Solutes have varying effects on properties such as density and viscosity.
		Some scientists attribute the low temperature anomalous nature of water to the presence of a second critical point; an interesting if somewhat unproductive hypothesis (as the attribution mixes cause with effect).
	www.lsbu.ac.uk /php-cgiwrap/water/pfp.php3?page=http://www.lsbu.ac.uk/water/anmlies.html (1144 words)

	Natuurwetenschappen.nl opmerking mbt warm water bevriest sneller
		Het wordt het Mpemba-effect genoemd, naar een Tanzaniaanse student, die het in 1969 opnieuw wereldkundig maakte.
		Dat heeft een koelend effect, en zorgt dat er minder water overblijft.
		En hoe minder water er is, des te sneller het bevriest.
	www.natuurwetenschappen.nl /modules.php?op=modload&name=Forums&file=viewtopic&topic=25&forum=6 (585 words)

	Kustom PC's Forums - View Profile: Mpemba Effect
		There is a fifth dimension beyond that which is known to man. It is a dimension as vast as space and as timeless as infinity.
		It is the middle ground between light and shadow, between science and superstition, and it lies between the pit of man's fears, and the summit of his knowledge.
		Mpemba Effect is not a member of any public groups
	forums.kustompcs.co.uk /member.php?find=lastposter&t=1941 (88 words)

	Chemistry and water question
		This eventually came to be called the Mpemba effect, named after a Tanzanian high school student in the 1960's.
		For a long time, many ice cream makers have made their ice cream using warmed milk since it can be made to freeze faster than cold milk.
		This article has all sorts of references to scientific work on this as well as a wonderful history of how the effect was discovered and why it's named after a Tanzanian high school student.
	www.toadwater.com /index.php?topic=15150.0 (746 words)

	Adirondack Forum - super cold weather lessons
		Some choose not to believe it, but this phenomenon can be demonstrated in your own freezer under the proper conditions.
		The quote cited seems to indicate that they tried quite diligently to obtain "the right result" (in the researchers mind that cold water would freeze quicker), but were unable to, even when trying to achieve that result.
		Overall I believe that the only reason there is an argument is because some "great" minds refuse to admit the possibility that their conventional thinking is wrongl.
	www.adkforum.com /showthread.php?t=335 (2790 words)

	Experiments with States of Matter: Mpemba Effect - Freezing Hot Water Faster than Cold Water
		The School for Champions is an educational website that helps you become a champion and encourages you to help others become champions too.
		The Mpemba Effect states that hot water changes its state from liquid to solid--or freezes--faster than cold water.
		The Mpemba Effect - Hot water Freezes before Cold - School for Champions
	www.school-for-champions.com /science/experiments/expmatterstates2.htm (630 words)

	Answer to the Mpemba effect. - Physics (Site not responding. Last check: 2007-10-30)
		Being the cooling heat transfer business for near 20 years, iv concluded the answer is far more simple (maybe) than scientists have found.
		all though this article http://math.ucr.edu/home/baez/physics/General/hot_water.html does describe other effects that probably effect the process along the way, its my belief that is mostly due to the more active molecules in warm water than the cold water, that allow it to reach freezing faster.
		Well you mite be thinking that once the temperature's of both samples become the same then the heat loss rate's also will be the same !.
	www.okka.biz /Answer_to_the_Mpemba_effect_-1933452-288-a.html (198 words)

	virus: virus: Re: The Tale of the Mpemba Effect (Site not responding. Last check: 2007-10-30)
		virus: virus: Re: The Tale of the Mpemba Effect
		virus: Re: The Tale of the Mpemba Effect
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	virus.lucifer.com /virus/2368.html (180 words)

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