On Jun 25, 3:08*am, dsi1 > wrote:
> On Jun 24, 7:16*pm, (Steve Pope) wrote:
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> > Jerry Avins > wrote:
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> > >> On Fri, 24 Jun 2011 02:54:58 -0400, Cheryl >
> > >> wrote:
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> > >> > My father, who WAS a physicist, was not convinced that a covered pot
> > >> > would boil faster than an uncovered pot. *I was always surprised when he
> > >> > said that. *Again I can't test because I only have one big burner on my
> > >> > electric stove top and the smaller ones don't seem to be evenly matched.
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> > >I can't see Cheryl's post, so I'll answer here. A covered pot boils
> > >faster because the cover prevents the faster molecules from escaping.
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> > This is another one Magee tested. *Turns out it does boil faster,
> > but the effect is not significant until heating the water is
> > farily far along. *Covering the pot just as it's approaching boiling
> > is sufficient to obtain almost all the benefit.
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> > Steve
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> This makes a lot of sense if most of the heat loss occurs when the
> water changes to steam and escapes into the room. Covering the pot
> recovers some of the latent heat by condensing it back into liquid
> water. I'll always try to cover the pot when boiling water - even if I
> have to use a cookie sheet or my big frying pan. Not doing so seems to
> be a waste of some good heat. :-)

Watch out! That cookie sheet will get hot where it projects over the
rim of the pot, especially with a gas stove.

Jerry
--
Engineering is the art of making what you want from things you can get.