Why is short track speed skating so silky? Can you elaborate on it?

There are three kinds of skates, including speed skates, figure skates and hockey skates. As the name implies, they are used for speed skating (including short track speed skating), figure skating and hockey respectively. According to the different needs of different sports, the shape, weight and even structure of different kinds of skates are different. Specifically, the blade of speed skating is the narrowest, only about1.4 mm. In contrast, the width of the widest figure skateboard is 3.5 mm, which can support the athletes to perform various complicated movements on the ice stably.

2. 1939, two scientists from Cambridge University suspected that the heat generated by the rapid friction between the skates and the ice during skating may be the main reason why the ice melts and forms a water film. Unfortunately, it turns out that the thickness of water film produced by friction heat will be obviously less than 20 μ m, and the roughness of ice itself is tens to hundreds of microns. In other words, the water film produced by friction can't even fill the "small puddle" on the ice, let alone provide effective lubrication. With the development of experimental technology, after 1960, scientists can gradually observe the microstructure of the ice surface accurately enough. When the temperature is not too low, the ice surface in contact with air will not change from regularly arranged water molecules to air, but has a transition layer. The transition layer has a gradually changing structure, from crystalline ice with orderly molecular arrangement to ice-water mixture, and then to a complete liquid water film. Micro-ice particles in ice-water mixture are connected by weak forces such as van der Waals force and hydrogen bond to form a porous structure, which can store liquid water like gel beads. The closer to the air, the more disordered the arrangement of water molecules in the transition layer. The more liquid water, the weaker the connection between solid ice crystals, and even tiny ice chips and particles that can move freely in the water film.

Under the condition that the radius and mass of turning trajectory are basically unchanged, you must have great centripetal force if you want to turn at high speed. Compared with single-edged skates embedded in ice at an angle of 90, grooved skates can be embedded in ice at a sharper angle, because they only contact with the sharp wedge on one side of the groove. Under the same positive pressure, the groove-side skates are embedded deeper into the ice, providing a larger stress area than the single-edged skates. Because when an athlete kicks the ice, the pressure between the skates and the ice is basically constant, so the larger the stress area, the greater the force.

4. At the same time, when the athletes' body inclination angle θ is the same, the groove skates are embedded in the side of the ice surface, and the ice surface is more vertical than the single-edged skates. According to the principle of vector decomposition of force, the horizontal component of resultant force is large. These factors ensure that groove-side skates provide greater centripetal force than single-edged skates in the horizontal direction. Therefore, the use of roller skates along the groove can make athletes not slow down when turning, and complete the transition between the two straights more smoothly.

With the development of experimental technology, after 1960, scientists can gradually observe the microstructure of the ice surface accurately enough. When the temperature is not too low, the surface of the ice layer in contact with air will not suddenly change from regularly arranged water molecules to air, but there is a transition layer. The transition layer has a gradually changing structure, from crystalline ice with orderly molecular arrangement to ice-water mixture, and then to a complete liquid water film. Micro-ice particles in ice-water mixture are connected by weak forces such as van der Waals force and hydrogen bond to form a porous structure, which can store liquid water, just like gel beads. The closer to the air, the more disordered the arrangement of water molecules in the transition layer, the more liquid water, the weaker the connection between solid ice crystals, and even micron-sized ice chips and particles that can move freely appear in the water film.