Why the ice is slippery?
The ice is considered the only slimming material in nature. Amazing, but scientists still do not know exactly why the ice is slippery. Most agreed that it’s all about the presence of a thin liquid water layer on its surface. And the reasons for this three: pressure, friction and the presence of free bonds of molecules.
For a long time it was believed that, if you press on ice, it melts, as water has an interesting property: in solid phase it is less dense than in liquid. For example, when riding ice skating is carried out on the ice, the temperature of its melting is reduced, part of the ice turns into water – and you slide. When drove, water freezes again.
At the same time, the more pressure, the lower the ice melting point will be. However, those fractions of degrees would not be enough for very cold weather when skates slide as easily. Yes, and if we assume that the blades of skates have a stronger pressure on the ice due to a small area of contact, why do we slip in ordinary shoes? Perhaps the reason is that friction heats the surface of the ice, due to which the water layer appears. But then another question arises: why, when we stand on ice without movement, all the same slip? It means that this explanation is little.
In 1850, the English chemist and physicist Michael Faraday guessed to lean each other two ice cubes. They frown. So the experimenter realized that the surface of the ice remains a solid without a liquid layer when not in contact with the air.
Modern scientists went further and suggested that in the inner layers of ice molecules less mobile due to breaking on the surface of hydrogen bonds. Consequently, surface molecules have enough energy in order to maintain the presence of a thin layer of water even at temperatures below 0 ° C.
In 2018, scientists from the Netherlands studied the glide of the steel ball on the ice at different temperatures. And came to the conclusion that very low friction is observed only in a limited range, typical of ice skating. Temperatures about -100 ° C lead to a slowdown of diffusion of molecules, and ice stops being slippery. And with an increase in temperature the number of molecules free from hydrogen bonds grow, which makes the ice more slippery. These findings were published in the journal of Journal of Physical Chemistry Letters.
No wonder skating is considered one of the oldest sports. The first officially fixed competitions on it were held in the UK in January 1763. Interestingly, in the theory of skating can be on Teflon. Energy required for slipping between crystalline teflon plates, small. Wear will be high, but also friction – Low.
