Editing Talk:1867: Physics Confession

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F1rst P0st http://www.explainxkcd.com/wiki/index.php/269:_TCMP [[Special:Contributions/172.68.141.190|172.68.141.190]] 07:54, 24 July 2017 (UTC)

Fuckin' ice skates, [https://youtu.be/_-agl0pOQfs?t=1m52s how do they work]? [[User:OldCorps|OldCorps]] ([[User talk:OldCorps|talk]]) 11:26, 24 July 2017 (UTC)

Any relation to #1489? They're both about things physicists don't understand. http://www.explainxkcd.com/wiki/index.php/1489:_Fundamental_Forces {{unsigned ip|172.68.132.5}}

<span style='font-style: italic; opacity: .5;'>Explain physics: It's 'cause Randall's dumb.</span> {{unsigned ip|141.101.104.47}}

;Explanation of skating
A lot of people both here and on Reddit seem to be talking about the pressure of the skates reducing the melting point. The pressure of the skates can only reduce the melting point by about 0.5C, so this is clearly not sufficient to produce a layer of liquid below -0.5C. The more correct explanation is that there is an ever-present layer of liquid on the surface of most crystals, including ice - this is the best explanation that exists right now and explains why ice skating stops being possible below around -30C (and is hard at intermediate temperatures). This is the explanation offered by most modern university courses on thermodynamics or materials science - here is an excerpt from a University of Cambridge materials science course: [https://imgur.com/a/8bZxG Excerpt] [[User:Jaredjeya|Jaredjeya]] ([[User talk:Jaredjeya|talk]]) 13:03, 24 July 2017 (UTC)

: I've just looked at the article linked in the explanation, whoever put it in didn't read the full article because it goes on to mention exactly this explanation. [[User:Jaredjeya|Jaredjeya]] ([[User talk:Jaredjeya|talk]]) 13:07, 24 July 2017 (UTC)
::Good ol' circular reasoning. [[User:OldCorps|OldCorps]] ([[User talk:OldCorps|talk]]) 15:48, 24 July 2017 (UTC)

"...ice skating stops being possible below around -30C".  Not true. I've skated at -40C. It's effing stupid, risk of frostbite in minutes, but still works. (Living North of 60 for 4+ decades)
: -40C? Ha! Try -40F! [[User:Davidgro|davidgro]] ([[User talk:Davidgro|talk]]) 23:55, 28 July 2017 (UTC)

: Ice skating works because ice is slippery and skates reduce the surface touching the ice which reduces the friction increasing how slippery it is. However, it is a special case of the question: "Why is ice slippery in the first place?" Which is not fully understood.[[Special:Contributions/162.158.114.16|162.158.114.16]] 11:27, 31 July 2017 (UTC)

A recent article discusses ice skating things [https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.041025 here]. Looks like the confined melted water film behaves oddly (viscoelastically) and unexpectedly gains ideal lubrication properties for skiing and skating. Surface hydrophobicity also affects sliding coefficients not by changing the thickness of melted films but rather the local water (complex) viscosity. However, they do not try this at -40 C (or -40 F as slyly pointed out above).