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General => Lobby => Topic started by: Darren Dirt on June 27, 2012, 01:09:21 PM

Title: hot water freezes more quickly than cold water -- WHY?
Post by: Darren Dirt on June 27, 2012, 01:09:21 PM
apparently SCIENTISTS STILL DO NOT KNOW WHY!
http://m.torontosun.com/2012/06/27/why-does-hot-water-freeze-faster-than-cold


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

Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Mr. Analog on June 27, 2012, 01:44:36 PM
The main problem is that there are a lot of variables at work, like convection.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Thorin on June 27, 2012, 01:48:48 PM
Hey, there's a $1,500 reward for figuring this out?
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Mr. Analog on June 27, 2012, 01:52:01 PM
Quote from: Thorin on June 27, 2012, 01:48:48 PM
Hey, there's a $1,500 reward for figuring this out?

Whoa, is it offered in the United States? If so: God did it.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Thorin on June 27, 2012, 02:00:08 PM
You didn't read that first link, did you?  The theory that god did it for yucks has already been floated, and has been marked as not precise enough to get the bounty.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Mr. Analog on June 27, 2012, 02:01:41 PM
Quote from: Thorin on June 27, 2012, 02:00:08 PM
You didn't read that first link, did you?  The theory that god did it for yucks has already been floated, and has been marked as not precise enough to get the bounty.

No LOL

Actually I'm pretty sure it's ThetansTM anyway, first John Travolta's haircut face combo and now hot water freezing before cold water.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Tom on June 27, 2012, 02:16:36 PM
Huh. I had thought it was proven that it really doesn't freeze quicker, its just that the volume of water goes down enough to freeze the water quicker since there's less of it.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Thorin on June 27, 2012, 02:28:18 PM
Darren, we might disagree sometimes, but at least I read your posted link.  And this was/is an interesting thread.

Tom, that theory has been floated as well but isn't the provable cause.  See the Wikipedia link in the first post.

I thought it was the lack of frozen top layer in the hot water that caused it, but it's not one single simple thing like that.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Darren Dirt on June 27, 2012, 03:36:21 PM
Quote from: Tom on June 27, 2012, 02:16:36 PM
Huh. I had thought it was proven that it really doesn't freeze quicker, its just that the volume of water goes down enough to freeze the water quicker since there's less of it.

My gut instinct (when in a sciencey mood) is that it's something to do with the molecules, their arrangement ... but does anyone know if this phenomena is just in WATER (H20) or is it in a lot of other liquids?


Because water is pretty wonky when it comes to what it does/doesn't do at certain temperatures and temperature changes, compared to most other substances in liquid form. Have the Experts tried to understand that stuff first i.e. analyze "a few frames within the whole moving picture" to then figure out why the overall film plays out the way it does? ... and is the freezing effect pretty much the reverse of http://en.wikipedia.org/wiki/Leidenfrost_effect ?
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Tom on June 27, 2012, 03:42:42 PM
Quote from: Darren Dirt on June 27, 2012, 03:36:21 PM
Quote from: Tom on June 27, 2012, 02:16:36 PM
Huh. I had thought it was proven that it really doesn't freeze quicker, its just that the volume of water goes down enough to freeze the water quicker since there's less of it.

My gut instinct (when in a sciencey mood) is that it's something to do with the molecules, their arrangement ... but does anyone know if this phenomena is just in WATER (H20) or is it in a lot of other liquids?


Because water is pretty wonky when it comes to what it does/doesn't do at certain temperatures and temperature changes, compared to most other substances in liquid form. Have the Experts tried to understand that stuff first i.e. analyze "a few frames within the whole moving picture" to then figure out why the overall film plays out the way it does? ... and is the freezing effect pretty much the reverse of http://en.wikipedia.org/wiki/Leidenfrost_effect ?
Wonky indeed. I think its the only liquid that expands when it transitions to a solid. Normally the molecules would get closer together as they slowed down, and they do, up till a point, then everything expands again.
Title: Re: hot water freezes more quickly than cold water -- WHY?
Post by: Darren Dirt on June 27, 2012, 10:23:32 PM
Quote from: Tom on June 27, 2012, 03:42:42 PM
expands when it transitions to a solid. Normally the molecules would get closer together as they slowed down, and they do, up till a point, then everything expands again.

(http://d24w6bsrhbeh9d.cloudfront.net/photo/236393_700b.jpg)