[Phys-l] Mpemba effect Was: Re: "Ask Marilyn"

[Bernard Cleyet <bernardcleyet@redshift.com>]

This is very old hat, since Aristotle!


Historical observations

Similar behavior was observed by ancient scientists such as Aristotle,[2] and early modern scientists such as Francis Bacon[3] and René Descartes.[4] Aristotle's explanation involved an erroneous property he called antiperistasis, defined as "the supposed increase in the intensity of a quality as a result of being surrounded by its contrary quality".


http://en.wikipedia.org/wiki/Mpemba_effect




But not until 1963 did the effect acquire a name, Mpemba the student w/ Osborn:

The ice-cream effect gained credibility and fame when Mpemba and D. G. Osborne of University College Dar es Salaam published an account of it inPhysics Education. 


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Hot Water Freezes Faster Than Cold Water. Why Does It Do So?

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by Jearl Walker
September, 1977
[the Amateur Scientist.  Sci. Am.]
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http://docs.google.com/viewer?a=v&q=cache:v7Ke7ka6A5gJ:myweb.unomaha.edu/~prmanley/manleyproject/documents/lesson%2520plans/heat/mpemba%2520effect.pdf+%2B%22american+journal+of+physics%22+mpemba+water&hl=en&gl=us&pid=bl&srcid=ADGEESjmL9ECIREs9h_ZdYVz1r60D2aB80PaZDBIpWTsWP4h4-n66r9wL6Tq1RUw36sj_VYGT8b5nv9vdcMbPmI4_uZuutSBOBNCHPHBdfcBA_Q1RVPENV4DNyrcfvnGedQhXmQtbCxP&sig=AHIEtbRUAhL79CRCAalBSACzezWoqc2ssw



bc has now read the article (current AJP), and finds all the above, and much more, is there.



On 2011, Jan 04, , at 16:50, carmelo@pacific.net.sg wrote:

> In the latest AJP, it is suggested that one may consistently observe  
> hot water freezing faster than cold water under certain conditions.  
> "For hot water at an initial temperature of > about 80°C and cold  
> water at < about 20°C, the cold water must supercool to a temperature  
> of at least about 5.5 °C, lower than the temperature to which hot  
> water supercools." Perhaps someone should email this paper to Marilyn  
> for comments.