Sv: Folks egna sanningar
Ju längre vatten kokat desto långsammare kallnar det.
Varmt vatten fryser fortare än kallt.
Den översta meningen tror jag inte på, men den andra finns det ju visst belägg för;
The Mpemba effect: When can hot water freeze faster than cold?
Author(s): Jeng, M (Jeng, M)
Source: AMERICAN JOURNAL OF PHYSICS Volume: 74 Issue: 6 Pages: 514-522 DOI: 10.1119/1.2186331 Published: JUN 2006
Times Cited: 8 (from Web of Science)
Abstract: We review the Mpemba effect, where initially hot water freezes faster than initially cold water. Although the effect might appear impossible, it has been observed in numerous experiments and was discussed by Aristotle, Francis Bacon, Roger Bacon, and Descartes. It has a rich and fascinating history, including the story of the secondary school student, Erasto Mpemba, who reintroduced the effect to the twentieth century scientific community. The phenomenon is simple to describe and illustrates numerous important issues about the scientific method: the role of skepticism in scientific inquiry, the influence of theory on experiment and observation, the need for precision in the statement of a scientific hypothesis, and the nature of falsifiability. Proposed theoretical mechanisms for the Mpemba effect and the results of contemporary experiments on the phenomenon are surveyed. The observation that hot water pipes are more likely to burst than cold water pipes is also discussed. (C) 2006 American Association of Physics Teachers.
SUPERCOOLING AND THE MPEMBA EFFECT - WHEN HOT-WATER FREEZES QUICKER THAN COLD
Author(s): AUERBACH, D (AUERBACH, D)
Source: AMERICAN JOURNAL OF PHYSICS Volume: 63 Issue: 10 Pages: 882-885 DOI: 10.1119/1.18059 Published: OCT 1995
Abstract: Temperature measurements taken near vessel walls show that initially hot water may well begin to freeze quicker than cold. This is not, as previously surmised, due to the cooling history of the water (e.g., air expulsion during heating). Rather, supercooling virtually always takes place. On those occasions where the cold water supercools sufficiently more than the hot the Mpemba scenario is the following: The hot water supercools, but only slightly, before spontaneously freezing. Superficially it looks completely frozen. The cold water (in larger volume than that of the hot sample) supercools to a lower local temperature than the-hot before it spontaneously freezes. This scenario can occur more often for ambient cooling temperatures between -6 degrees C and -12 degrees C. (C) 1995 American Association of Physics Teachers.
