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Ice skating is traveling on ice with skates, narrow (and sometimes parabolic) blade-like devices moulded into special boots (or, more primitively, without boots, tied to regular footwear). It is mainly done for recreation and as a sport. It is possible on canals and lakes, etc. after it has been freezing for some time, and at indoor and outdoor skating tracks and areas with artificial cooling. The skating rink regarded as the world's longest (about 8 kilometres long) is the Rideau Canal located in Ottawa, Ontario, Canada. In some countries with a temperate climate, e.g. the Netherlands, frozen canals and lakes are fairly rare, but skating is popular where these are encountered.
History Prehistory The exact time and process by which humans first learned to ice skate is not known, though archaeologists believe the activity was widespread. The convenience and efficiency of ice skating to cross large, icy areas is shown in archaeological evidence by the finding of primitive animal bone ice skates in places such as Russia, Scandinavia, Great Britain, Germany, and Switzerland. The runners were made from bones of cattle. They ground down until they formed a flat gliding surface, and thongs tied them to the feet. • Earliest historical documentations The first concrete mention of ice skating is found in a book written by William Fitzstephen, a monk in Canterbury. In his book about Thomas Beckett, he writes the following, a description of a scene taking place below the northern city walls of Canterbury during the winter: ...if the moors in Finsbury and Moorfield freeze over, children from London play. Some of the children have attached bones to their ankles, and carry well-worn sticks. They fly across the ice like birds, or well-fired arrows. Suddenly, two children will run at each other, sticks held high in the air. They then attack each other until one falls down. Often, the children injure their heads or break their arms or legs... The sticks that Fitzstephen refers to were used for movement, as the primitive bone-made ice skates did not sharp gliding edges like modern ice skates. The first depiction of ice skating in a work of art was made in the 15th century, by the Dutch artist Johannes Brugman. The picture, of Saint Lidwina, patron saint of ice skaters, falling on the ice was the first work of art by a major artist to feature ice skating as a main theme. Another important aspect of the painting is a man seen in the background, who is skating on one leg. This means that the ice skates the man was wearing must have sharp edges similar to those found on modern ice skates. Development of skates Adding edges to ice skates was invented by the Dutch in the 13th or 14th century. These ice skates were made of steel, with sharpened edges on the bottom to aid movement. The construction of modern ice skates has remained largely the same. The only other major change in ice skate design came soon after. Around the same time period as steel edges were added to ice skates, another Dutchman, a table maker’s apprentice, experimented with the height to width ratio of the metal blade of the ice skates, producing a design that remains almost unaltered to this day. The user of the skates no longer needed to use sticks for propulsion, and movement on skates was now freer and more stable. Social status of ice skating
How it works Ice skating works because the metal blade at the bottom of the ice skate shoe can glide with very little friction over the surface of the ice. However, slightly leaning the blade over and digging one of its edges into the ice ("rockover and bite") gives skaters the ability to increase friction and control their movement at will. In addition, by choosing to move along curved paths while leaning their bodies radially and flexing their knees, skaters can use gravity to control and increase their momentum. They can also create momentum by pushing the blade against the curved track which it cuts into the ice. Skillfully combining these two actions of leaning and pushing - a technique known as "drawing" - results in what looks like effortless and graceful curvilinear flow across the ice. Experiments show that ice has a minimum kinetic friction at −7°C (19°F), and many indoor skating rinks set their system to a similar temperature. The low amount of friction actually observed has been difficult for physicists to explain, especially at lower temperatures. On the surface of any body of ice at a temperature above about −20°C (−4°F), there is always a thin film of liquid water, ranging in thickness from only a few molecules to thousands of molecules. This is because an abrupt end to the crystalline structure is not the most entropically favorable possibility. The thickness of this liquid layer depends almost entirely on the temperature of the surface of the ice, with higher temperatures giving a thicker layer. However, skating is possible at temperatures much lower than −20°C, at which there is no naturally occurring film of liquid. When the blade of an ice skate passes over the ice, the ice undergoes two kinds changes in its physical state: an increase in pressure, and a change in temperature due to kinetic friction and the heat of melting. Direct measurements show that the heating due to friction is greater than the cooling due to the heat of melting. Although high pressure can cause ice to melt, by lowering its melting point, the pressure required is far greater than that actually produced by ice skates. Frictional heating does lead to an increase in the thickness of the naturally occurring film of liquid, but measurements with an atomic force microscope have found the boundary layer to be too thin to supply the observed reduction in friction. Sports based on ice skating A number of sports, and recreational activities are based on the principle of ice skating: | ||||||||||
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