why is ice so slippery?
Most of the slippery materials we know of are liquid, like oil. But how can a solid be slippery?
The answer lies on the fact that the density of ice is lower than that of water. That is unusual. Normally, the solid is denser than the liquid and the liquid denser than the gas. In this case, the gas is water vapour, the liquid is water and the solid is ice.
Icebergs and ice cubes- Rocks that float!
Ice floats because its density is lower than that of the surrounding water.
If we apply pressure on ice, for instance by means of stepping on it, we cause it to melt on the region where the pressure is being applied, and the water produced in this way causes it to be slippery. The pressure applied by an ice skate blade will be even higher, because of the smaller surface area of the blade when compared to feet (force and pressure), and as a result more melting of the ice is produced, resulting on more slipperyness.
When pressure is applied to ice, it is forced into a smaller volume and that favours its transition to the liquid state (water) because it occupies a smaller volume! When pressure is removed, it will be able to expand and make the transition to ice again (provided the temperature is appropriate, off course).