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CCWilson
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Are there changes in the appearance and characteristics of ice as the temperature continues to fall? Say at -30 C, -60 C, etc? Does it remain slippery? Is there a point where it breaks up?
That's an old meme that is simply wrong. It's in lots of textbooks, it's taught in schools, but it's wrong. The temperature at which the water/ice transition occurs does drop with increased pressure, but this effect is very small. The amount by which the heaviest of ice skaters putting all of their weight on one blade reduces the melting point is tiny.SteamKing said:Ice is slippery only because applying pressure temporarily causes the surface to re-liquefy.
Crazymechanic said:But it has to do with pressure I guess even speaking about the layers , because imagine a heavy iron block that is mounted on four needles would you be able to move it on ice ? No because the weight would put so much pressure on such a tiny area that the needles would have a huge grip.
Now make those needles or whatever with a slightly bigger surface contact area and slowsly you reach a point were you can just slide on ice.
I guess it still has to do with the force you put upon a given area to see if something slides on a surface of ice or not.
D H said:That's an old meme that is simply wrong. It's in lots of textbooks, it's taught in schools, but it's wrong. The temperature at which the water/ice transition occurs does drop with increased pressure, but this effect is very small. The amount by which the heaviest of ice skaters putting all of their weight on one blade reduces the melting point is tiny.
There are two main lines of thought about why ice is slippery. One is friction. The friction of a blade sliding over unmelted ice causes the ice to melt. That's not the leading idea, however.
The dominant view is that ice is slippery because of boundary layer effects. The surface of ice has a thin boundary layer that acts a whole lot like liquid water. Pressure is not needed, nor is friction. This boundary layer is always there. It's observable with electron microscopes. The thickness of this boundary layer varies with temperature. It's but a molecule thick at very cold temperatures (~ -150 C). The layer is considerable thicker at temperatures near freezing. We can skate on ice because we're not skating on ice. We're instead sliding on a thin layer of water-like ice that is always present.
This is certainly is what was taught for a long time, and apparently still is taught in some circles.technician said:If you are going to make general statements about what is 'taught in schools' then you should back them up some how.
D H said:The dominant view is that ice is slippery because of boundary layer effects. The surface of ice has a thin boundary layer that acts a whole lot like liquid water. Pressure is not needed, nor is friction. This boundary layer is always there. It's observable with electron microscopes. The thickness of this boundary layer varies with temperature. It's but a molecule thick at very cold temperatures (~ -150 C). The layer is considerable thicker at temperatures near freezing. We can skate on ice because we're not skating on ice. We're instead sliding on a thin layer of water-like ice that is always present.
LastOneStanding said:That has nothing to do with the slipperiness of ice. All that shows is you can dig into the ice and get a grip on it because its not impermeable.
The freezing point of water is 0 degrees Celsius or 32 degrees Fahrenheit.
As the temperature drops, the molecules in water slow down and come closer together. At 0 degrees Celsius, the molecules are packed tightly enough to form a solid structure, creating ice.
No, the temperature of ice remains constant at 0 degrees Celsius until all of it has melted. This is because the energy from the surrounding environment is being used to break the bonds between the water molecules, rather than increasing the temperature.
Yes, ice can exist at temperatures below 0 degrees Celsius. This is because the actual temperature of ice is not determined by the temperature of its surroundings, but rather by the energy required to break its molecular bonds.
The density of ice decreases as the temperature decreases. This is because the molecules in ice are further apart than in liquid water, resulting in a lower density. This is also why ice floats on top of water.