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Old 2021-01-02, 13:40   #4181
Xyzzy
 
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Old 2021-01-02, 14:26   #4182
LaurV
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Misleading. Hot water freezes FASTER (and easier) than the cold water. It is called Mbassa's law, or something like that (it was also discussed on the forum long ago, IIRC).

Edit: Mpemba effect, sorry. Nice story to be read, here.

Last fiddled with by LaurV on 2021-01-02 at 14:30
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Old 2021-01-02, 17:05   #4183
Dr Sardonicus
 
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I note that the temp in the video is said to be -41.

It happens that -40, besides being the temperature at which the Fahrenheit and Celsius scales coincide, is also known as the "Schaefer point." When the temperature gets this low, if the air is supersaturated with water vapor, the excess spontaneously "nucleates" and freezes out in tiny ice crystals.

It is also very close to the freezing (or fusion or solidification) point of mercury.

In the Jack London story To Build a Fire, a man sets out alone despite it being below -40, which he learned by spitting and hearing his spit freeze and crackle before it hit the ground. He had been warned not to set out alone when it was below -40.
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Old 2021-01-02, 18:32   #4184
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Quote:
Originally Posted by Dr Sardonicus View Post
I note that the temp in the video is said to be -41.

It happens that -40, besides being the temperature at which the Fahrenheit and Celsius scales coincide, is also known as the "Schaefer point." When the temperature gets this low, if the air is supersaturated with water vapor, the excess spontaneously "nucleates" and freezes out in tiny ice crystals.

It is also very close to the freezing (or fusion or solidification) point of mercury.

In the Jack London story To Build a Fire, a man sets out alone despite it being below -40, which he learned by spitting and hearing his spit freeze and crackle before it hit the ground. He had been warned not to set out alone when it was below -40.
In Northern Ontario as a young teen I would go ice fishing (for trout) in -40 temperatures. When the wind would whip up, you would feel cozy beside the lean-to and small fire which would keep your tea (from pine needles) hot. Taking a leak was a process because you didn't want to freeze anything and no, I never saw my pee freeze before it hit the snow. If you cut yourself you would bleed for a very long time due to the cold so you would "chum" your augered hole with your blood. Keeping a corked flask half full of hot water kept the hole ice free. Coming back at night, the sky would be full of stars and the green-blue northern lights would range all over it. If there was no wind, the fresh snow would crunch under your boots, you would need to breathe either through a scarf or slowly, the dark forest with the tall conifers quiet and welcoming..it would be silent all around. The walk back was about two hours and the chimney smoke from the wood fires from some of the houses in town could be smelled before seen rising straight up.
During this time, mid- seventies, I read the Reader's Digest regularly and looked forward to stories and jokes inside. There was a Jack London story about an old grizzled boxer in a bar and a younger brash fellow full of himself who was looking to pick a fight with him. The older man described his arthritic knuckles, the scars he earned as well as the broken bones to the younger man to let him know he would not back down and that he would take no pleasure in beating him. I would really like to know the title of this story to find it again..it's not "A Piece of Steak."
Let's have a better 2021 (and expeditiously get rid of some of the clutter still lingering in the meanwhile...anyone know what a Klingon is?..it's what won't let go after you wipe your rear end)

Addendum: Thanks LaurV for your posting of the Mpemba effect! Here is a link to an article which should be read alongside: https://arxiv.org/ftp/arxiv/papers/2010/2010.07287.pdf
.

Last fiddled with by jwaltos on 2021-01-02 at 18:53 Reason: corr
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Old 2021-01-03, 19:04   #4185
kladner
 
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Default SS La Palma

http://www.oceanlinermuseum.co.uk/Oc...rs_Portal.html
La Palma is the second ship on the link. It is the last survivor of the Titanic era, built a year before my father's birth.
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Old 2021-01-09, 16:46   #4186
xilman
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This is an amazing bit of engineering!

https://twitter.com/i/status/1347943803223736321
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Old 2021-01-09, 17:36   #4187
pinhodecarlos
 
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Swaffham Prior plans to become the UK’s first village to switch to zero-carbon heating by connecting most homes to a shared network that taps naturally occurring warmth via ground and air source heat pumps. More on the link below and happy to be part of the team delivering this project.



https://www.thetimes.co.uk/article/s...zero-2vr7hlmz9
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Old 2021-01-09, 18:36   #4188
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https://www.wired.com/story/how-outrun-dinosaur/
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Old 2021-01-09, 18:49   #4189
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Quote:
Originally Posted by Xyzzy View Post
That reminds me of this video I took about two years ago:
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Old 2021-01-09, 19:00   #4190
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Quote:
Originally Posted by MooMoo2 View Post
That reminds me of this video I took about two years ago:
I have enjoyed doing that demonstration for people. I leave the cap on, show that it is liquid, then squeeze the bottle. Evian is not a bad choice as it has a low TDS (4 ppm).
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Old 2021-01-09, 23:11   #4191
kladner
 
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Quote:
Originally Posted by xilman View Post
This is an amazing bit of engineering!

https://twitter.com/i/status/1347943803223736321
Wow! Mesmerizing!
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