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

[chuck britton <cvbritton@mac.com>]

It was certainly true in our frost filled freezer in the '50's.
The (metal) ice cube tray filled with hot water 
would melt into the (thick) frost layer, giving 
better thermal contact (or such was my thinking).


At 10:00 PM -0800 1/5/11, Bernard Cleyet wrote:
> 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.
>
>
> ----------------
>
> Hot Water Freezes Faster Than Cold Water. Why Does It Do So?
>
> ---------------------
>
> by Jearl Walker
> September, 1977
> [the Amateur Scientist.  Sci. Am.]
> ---------------------
>
>
> 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.
>
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