Why is the ice knife as sharp as a knife

Ice skating is a popular ice sport that improves fitness, balance, cardiovascular function, relaxation and stress. Talking about skating, people have to talk about flying on the ice when a good friend - skates. The key to skates is that sharp skates, about skates, what little knowledge?

Why ice skates like "knives"?

It is well known that we walk on the ground by the friction between our shoes and the ground, without which it would be difficult to move. But for skating, too much friction is not enough, and for smooth skating, less friction is needed.

The skater can not only allow the skater in the start and acceleration phase to quickly get forward momentum, but also can reduce the friction when sliding, and maintain stability.

So the question is, why is there so little friction between ice and skates, both solid? You can imagine that by putting a layer of fluid between solids, friction is greatly reduced, and lubricants work on this basis. Scientists have studied the contact surface between the skates and the ice, and found that the reason for the low friction is that there is a layer of water between the skates and the ice, which plays the role of lubrication.

But where does this water film come from? It starts with the shape of the skates.

Ice knife looks like a "knife" with a very thin edge. The blade of an ordinary ice knife is only 2mm wide, and the blade of a pattern ice knife is only 4mm wide. The front of the knife is crescent shaped and the center is concave. Therefore, the contact area between the skates and the ice is very small. And the pressure of the ground is certain, put on skates, the force area of the ice is reduced, the pressure will greatly increase.

According to scientific studies, ice melting has a characteristic: when the pressure is increased, the melting point of ice will decrease. Generally, the melting point of ice will decrease by 0.0075℃ for every increase of standard atmospheric pressure. In this way, the thin, sharp blades accelerate the melting of sub-zero ice.

Of course, there are other explanations for how this film of water forms, including "frictional melting", which suggests that the rapid friction between the skates and the ice creates heat that speeds up the melting of the ice surface.

Such as "surface melting said" think again, this is the surface of a thin layer of ice is similar to liquid water, no completely frozen, even below the freezing point, because when water freezes, every molecule of water by hydrogen bonding, seize the surrounding water molecules to form crystal structure, but the surface of the water molecules around the lack of other water molecules, Instead of forming a regular structure like the one inside an ice cube, it just drifts around the surface in disorder, and when the skater makes contact with the ice, it doesn't require too much pressure for the water to lubricate the surface of the ice.

Whatever the theory, it is generally believed that the thin film of water between the skater and the ice lubricates it, reducing the friction between the skater and the ice, allowing the skater to run on the ice or perform many beautiful movements.