We seem to have a contradiction here. RWG says that, experimentally, the larger droplets run down first, while Veit theorizes that the smaller ones go first. I would theorize that as the surface tensions of all droplets decrease, gravity overcomes surface tension first on the heavier droplets. -- Gene ________________________________ From: Veit Elser <ve10@cornell.edu> To: math-fun <math-fun@mailman.xmission.com> Sent: Mon, April 25, 2011 4:41:32 PM Subject: Re: [math-fun] Do sweat it The radiative heat flow to the droplets goes like their area on the glass, but the heat required to raise their temperature by one degree goes like their volume. The small drops therefore heat up faster than the large drops and their surface tension diminishes faster, causing them to become unstable (against gravity) first. Veit On Apr 25, 2011, at 7:18 PM, Bill Gosper wrote:

Sprinkle some water on the horizontal inside surface of the opened glass door of a room-temperature toaster oven. Close the door, and wait half a minute for the larger drops to run down. Press TOAST. What happens to the remaining drops?

I would have expected them to evaporate. Instead, they run down in decreasing order of size, at least for me, well before reaching the boiling point. Why?? --rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun

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