Non-Friction or Frictional?

February 21, 2006 4:13 PM

Why is Ice slippery? You would have thought this would be well defined in 2006. But scientists are still arguing about the key elements. Plus no clear definition of Ice IX...
posted by somnambulist (23 comments total)

Fascinating article. I didn't know there were different types of ice.
posted by brundlefly at 4:43 PM on February 21, 2006

I imagine a man in goggles and lab coat rubbing two ice cubes together. A small crowd of other scientists whisper amongst themselves quietly as they watch on. Taking notes on their clipboards whenever something spectacular happens, for instance, when the two cubes fuse, or when they do not fuse. Later, there is much spinning of vials!
posted by TwelveTwo at 4:50 PM on February 21, 2006

Why is ice slippery? I always sort of assumed it was a combination of "friction causing melting" and "the surface layer of water isn't actually frozen".
posted by Jimbob at 4:50 PM on February 21, 2006

Ice IX is a metastable form of solid water that exists at temperatures below 140K and pressures between 200 and 400 MPa. It has a tetragonal crystal lattice and a density of 1.16 g/cm³, slightly higher than ordinary ice.

Ice-9, on the other hand, is something you should hope never to find in your gelato.
posted by JekPorkins at 5:04 PM on February 21, 2006

Slippery when wet.
posted by darkstar at 5:07 PM on February 21, 2006

They should have been asking this at the olympics with the gadzillion falls in the figure skating competition.
posted by matkline at 5:16 PM on February 21, 2006

TwelveTwo, your post made me feel warm and fuzzy for some reason.
posted by culberjo at 5:18 PM on February 21, 2006

You must be a scientist.
posted by TwelveTwo at 5:19 PM on February 21, 2006

MetaFilter: There will be much spinning of vials!

(I had to try it at least once)
posted by Clamwacker at 6:02 PM on February 21, 2006

I always assumed it had to do with the structure of crystalline water not offering a grippy surface. Water's a very simple molecular structure, not very convoluted or bumpy. How slippery is frozen Helium, for example? Though I suspect that occurs at temperatures too low to be meaningful. Nor does it have the hydrogen bonds that keep water so tightly bound to itself in the lattice.

Someone solve this, quick! I'm flashing back to high school chemistry.
posted by Eideteker at 6:09 PM on February 21, 2006

Thank you for this post!
posted by Protocols of the Elders of Awesome at 6:46 PM on February 21, 2006

The 2006 World Ice Art Championships begin this Sunday, February 28th in Fairbanks, Alaska. The weather forecast looks great!

Images of 2005 winners are listed here and here; 2002-2004 winners here. Many are ethereally beautiful.
posted by cenoxo at 7:30 PM on February 21, 2006

For those wanting to be amazed even more by water: Forty-one Anomalies of Water ¹
posted by MikeKD at 7:53 PM on February 21, 2006

Water is god.
posted by TwelveTwo at 8:37 PM on February 21, 2006

The scientists started considering what happens to tectonic plates after they are pushed back down into Earth's interior. At about 100 miles down, the temperature of these descending plates is 300 to 400 degrees — well above the boiling point of water at the surface — but cool compared with that of surrounding rocks. The pressure of 700,000 pounds per square inch at this depth, Dr. Bina and Dr. Navrotsky calculated, could be great enough to transform any water that was there into a solid phase known as Ice VII.

Now that's something to bring up at parties. But only the kind of party TwelveTwo mentioned.
posted by Citizen Premier at 10:20 PM on February 21, 2006

I so want to go to one of twelvetwo's parties.

Excellent post, thanks.
posted by Matt Oneiros at 10:45 PM on February 21, 2006

Water is god.

And I am mostly water. Hooray!
posted by stavrosthewonderchicken at 11:13 PM on February 21, 2006

Water is god

I think cities would be a lot more aesthetically pleasing and we'd all be a lot better off if we incorporated flows of water in them. Above-ground aqueducts, waterfalls, fountains, whatever. Everyone should be within walking distance -- and definitely able to see -- a lake or an ocean or a sea.

Landlocked North American cities definitely seem to be missing something. A lot of somethings. Of course, I'm probably biased from growing up in one.
posted by blacklite at 2:43 AM on February 22, 2006

Interesting, but I don't buy the explanation for the pressure effect being negligible; the picture clearly shows that the blades of ice skates are curved, with only a fraction of the available surface area in contact with the ice. This means that a 150 pound woman would exert a pressure much greater than 150 PSI on the ice.

Now ice IX; that's scary stuff.
posted by TedW at 5:30 AM on February 22, 2006

Ice 9 has something to do with seeds and the ways cannonballs can be stacked. Or Bokononism.
posted by nofundy at 6:14 AM on February 22, 2006

I think its just a bunch of foma
posted by TedW at 6:35 AM on February 22, 2006

I'm with TedW on this.
posted by nofundy at 7:14 AM on February 22, 2006

Mod note: The short answer is, it's just slippery.

The San Francisco Chronicle did a similar article and diagram.

"Why is Ice Slippery?" PDF from the December 2005 Physics Today.

Michael Faraday, who also invented the dynamo, was the first scientist to suggest that the surcface of ice always thin film of water.

This Exploratorium article has some interesting stuff, like the difference between "fast ice" and "slow ice" and why the ice used for hockey is colder than the ice used for figure skating (it's warmer, and softer, for figure skating).

Even ice that is 200 degrees below zero Fahrenheit (-129 Celcius) or more still has this layer.
...
At about 250 degrees below zero Fahrenheit (-157 centigrade), the ice has a slippery layer one molecule thick.

posted by kirkaracha (staff) at 9:55 AM on February 22, 2006