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Why is ice slippery?

6 Answers
The quality of slippery-ness seems to apply to so many totally different sorts of material/ substances, what causes it?
G

"slippery-ness" occurs as a function of how tightly molecules are bonded together. In the case of water/ice it is the fact that the water molecules in water can move freely past one another that creates the slick feeling. If you then note that water cannot be compressed between two non pourous surfaces, you end up with a film of liquid between the surfces. If this liquid cannot escape from between the surfaces effectively then the two surfaces are separated by a material whose molecules are loosely bonded, this allows the two surfaces to slide across each other easily and be "slippery". There are many other "slippery" materials, and their apparent "slippery-ness" occurs as a function of their viscosity (ability for molecules to slide past each other) and their ability to form a film between two surfaces. Any sufficiently viscous material that can form an effective film between two surfaces will appear to be "slippery"

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D

Ice in itself is not slippery. Only when some of the ice melts (often a thin layer on the outside surface), then the small amount of water that forms on the surface of the ice is what makes the ice "slippery". This is why ice is rarely regarded as dangerous, but "black ice" is considered quite scary, because of how slippery it is.

Black ice black ice can form on roadways when the moisture from automobile exhaust condenses on the road surface, wetting the "dry, non-slippery" ice, and making it extremely slippery.

Think of it like a cube of ice that you take freshly from your freezer tray, you can hold the cube easily. But if you drop the cube in a glass of water first, then try again, you see that it becomes much harder to hold the cube with your fingers, because it's too slippery now.

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S

But people...WATER is not generally slippery... and other surfaces are slippery when NOT wet. What is the quality of slippery-ness from? That's what I'm after. I guess this is a physics question. To say it is "the smoothness" is to beg the question. I guess in way, there is no slippery-ness until there is more than one surface - it is how one thing interacts with another? It can't just be about temperature -- glass, silicone, vaseline-- these are "slippery" too. The viscera in an animal is "slippery." Biological substances sometime seems slippery by function. What is the common denominator?

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G

Ice is not slippery in and of itself. Ice is a solid made of tightly packed water molecules. This solid is resistant to the more loosely packed molecules in liquid water, therefore if the surface of ice is melted by a source of heat (say the touch of a finger), the liquid fills the gap between the ice surface and the finger. This liquid water between the two surfaces acts as a lubricant making the ice appear to be slippery.

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P

It is assumed that a smooth surface is slippery while a rough surface is not. However this is not true with ice. Ice is slippery not due to its being smooth but because its melting point decreases when pressure increases.

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L

The smoothness

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