Fun Science at the Winter Olympics

Compared with the scorching sun and the heat of the Summer Olympics, the Winter Olympics, covered in snow and snow, have a different charm and scenery. Here is a journey as white as jade, a stadium as crystal clear as a mirror, a jumping platform with a “broken bridge in danger”, and a steep and winding slide. Athletes who step on skates and snowboards are galloping like the wind and want to fly; the brave ones who drive sleds have created the land limit speed, known as “Formula 1 on ice”.

Figure skating was established for the first time in the 1908 London Olympics, but the “summer and winter season” of the early Olympic Games was indeed reluctant. In 1924, the Paris Olympic Games in France held the ice and snow events in Chamonix six months ahead of schedule and called it the “Eighth Olympia International Sports Week”, which was later “posthumously recognized” by the International Olympic Committee as the first Winter Olympics.

When the “White Olympics” went from “vassal status” to a separate portal, and the five-ringed flag fluttered alternately in the two seasons of the earth when the cold and summer are distinct, the Olympic Games will be more colorful and full.

It is not wrong to say that the Winter Olympics is a kind of “water sports”, because ice and snow are solid water. Although 71% of the earth’s surface is covered by water, and 2% of the water is in the form of ice, our understanding of water and ice is still quite superficial, including the complex mechanics of human movement on ice and snow.

In 2007, Canada’s Wotherspoon set a world record in 500-meter speed skating with a time of 34.03 seconds, with an average speed of 14.69 meters per second. Jamaica’s Powell set the world record for the men’s 100-meter dash in the same year at 9.74, with an average speed of 10.27 meters per second. Skating is arguably the fastest way for humans to move across the surface of the earth with their feet.

Records of ice skating date back more than 4,000 years to Scandinavia. The tibia and ribs of deer and cows are tied to the feet, which is the earliest prototype of skates. In 1250, iron ice skates mounted on wooden boards appeared in Holland. In 1572, the Scots invented the first pair of all-iron skates, which marked the birth of modern skates.

Why can’t ice skates glide on cement, glass, and steel plates, but they can dance freely on the ice and “do it with ease”?

Many articles and textbooks have told us that firstly, due to the pressure of the ice blade, the melting point of the ice is lowered, and at the same time, due to frictional heat generation, the ice at the contact point melts rapidly, thus creating a thin film of water between the blade and the ice surface. play a lubricating role. There are also many scientists who have always questioned this explanation, thinking that the pressure and friction of the ice blade alone are far from enough to melt the ice surface.

Research in recent years has confirmed that ice forms a liquid layer with a thickness ranging from a few water molecules to several thousand water molecules, even when the ambient temperature is well below its melting point. This is because each water molecule in the ice layer is “fixed” by the adjacent molecules up, down, left and right, while the surface water molecules can only be connected with the “lower” molecules, and the vertical vibration speed is faster, so the stable crystal structure is lost. , behaves in a “semi-liquid” state even at temperatures well below the melting point. The great significance of this discovery is that the “smoothness” of ice is mainly its own natural property, rather than the effect of external forces.

Skating is undoubtedly the most stretched, smooth, light and dexterous sport. The body squatting and bending, alternating legs, kicking the ice, closing the legs, lowering the knife, and sliding in. The athlete swept across the ice like a shooting star, leaving a beautiful arc behind him. We seek the least resistance when gliding, but we need the greatest resistance when pedalling to gain power. Therefore, the long axis of the skate on the foot where the body’s center of gravity is located must be consistent with the forward direction, but the force direction of the kicking foot must be perpendicular to the long axis of the skate, and the sharp blade “cuts” into the ice layer to “eat the ice”.

Contrary to the blade of a kitchen knife, the blade of an ice blade is an arched groove. The medium and long-distance speed skating knives need to maintain good linearity, so the blade is longer; the short-track speed skating knives have relatively short and high blades, so that the skates will not be able to move forward in the arc and when the inclination is large. contact with ice. Ice hockey players run from left to right, figure skaters toss and jump, and the requirements for flexibility and change are better than the requirements for straight-line speed. Therefore, the blade of the ice skate has a short blade, a sharp blade, a deep blade, and a row of “serrations” at the front can better Control sudden stops.

At the 1998 Nagano Winter Olympics in Japan, almost all world records for speed skating were broken, and then at the 2002 Salt Lake City Winter Olympics in the United States, all world records were set again, leading to the direct impact of this “ice revolution”. The reason is the Kleip skate, which is nicknamed “flipper” by athletes.

When we run and jump, the muscles of the hip, knee, and ankle joints work together in a natural order. However, in the traditional skating action, since the front and rear ends of the skates and the skate are fixed, if the ankle joint is stretched when the ice kicking action is completed, the tip of the knife will “shave ice”, which will increase the resistance at light, and lose the balance in the heavy, so the ankle joint must be controlled. Plantar flexion and “locking the ankle” as a technical point, thus “killing” the strength of the ankle muscles, and only relying on the knee and hip muscles to “work”.

The ingenious idea of ​​Kleip Skate is to connect the front blade holder of the blade to the skate with a hinge, and the rear blade holder can be separated from the skate at any time. Its core value is to “liberate” the ankle, so that when the athlete moves the center of gravity forward, the back knife holder and the heel are automatically disengaged, so that the ankle joint and metatarsal joint can be freely stretched in the final stage of the ice kick, and still maintain the “full edge” of the skate. “On the ice”, the knee joint strength can be fully exerted as a result. The Kleip Skate actually turns the foot of the traditional skates around the tip of the blade into a rotation around the sole of the foot, shortening the “heavy arm” of the body, and at the same time overcomes the disadvantage that the center of gravity mainly moves laterally when kicking the ice, so that the center of gravity of the body can move forward longitudinally. . Statistics show that the Kleip ice skate can increase the sliding speed of the middle and long distance competition by 5%, and the average lap (400 meters) is 1 to 1.5 seconds faster.

The white snow has always been the source of inspiration and ingenuity for poets and painters, and it is also the noble and elegant background of the Winter Olympics. Snowboards are essential basic equipment for athletes. When a person stands on both feet, the pressure on the ground is about 15,000 Pa. When walking on the snow-covered field, each foot must compact the soft snow, so it will consume a lot of energy and “walk with difficulty”. The snowboard increases the snowboard area by 20 times, and the pressure of the foot on the snow is also reduced to 1/20 of the original.

The surface of snow is perhaps one of the most amazing surfaces on Earth, where solid, liquid, and gaseous water coexist and interact to form complex physical properties. Skiing can be seen as the synthesis of the rotation of the center of gravity of the adult-board system and the curve movement. Alpine skiing is a direct demonstration of the conversion of gravitational potential energy into kinetic energy, and a heavier athlete experiences less air resistance per unit body weight and therefore slides faster. When turning big or small, not only do you rely on the poles in your hand to change the direction of travel like a pole, but also rely on the body to tilt to form an angle between the bottom surface of the skis and the snow surface. After the high-speed sliding edge is “carved” into the snow, the lateral friction force of the “side cutting” is perpendicular to the edge of the ski, providing the centripetal force of the human body’s curved movement. The new type of snowboard has a wider head and tail and a thinner waist, which is shaped like an “hourglass”, and will form a certain arc to “guide” the turn after applying force. The shorter the ski, the narrower the “waist”, the smaller the turning radius, and the ski without bending deformation cannot turn.

Modern snowboards can automatically “trip” for safety after an athlete falls. In order to reduce friction and protect skis, “waxing” is an important skill that athletes must master.

Ski jumping is the most spectacular and exciting event in the Winter Olympics. From the more than 100-meter-long slideway, the 37-degree steep slope is sharply reduced to a gentle slope of about 11 degrees at the end. The athlete takes off at a speed of 100 kilometers per hour at the take-off point, and the spread is wide and long. The snowboard “flyed” for about 6 seconds and landed at point K at 90 or 120 meters. Although the towering platform is as high as tens of meters, the relative height of the athlete’s body and the ground is always only a few meters, and the arc of the slope is roughly parallel to the athlete’s parabolic trajectory in the air. When the athlete finally landed at a very small angle, the impact force perpendicular to the ground is far less than that of track and field events such as the triple jump, not to mention that there is a 40-centimeter-thick layer of snow cushioning. . Ski jumping can be regarded as a “downward throwing motion” of the human body, and it can also be regarded as a “takeoff” and “landing” of a “flying object”.

The “summer jumping platform” that is popular in the world today uses special tiles and a water spray system to build the slide rails of the slideway, and uses the elastic foam plastic with minimal friction to lay the “landing area” of the hillside. Not only has it become a training base for ski jumpers all year round, but it has also become a new favorite in the tourism industry to attract the public.

The biggest crisis of the 1932 Lake Placid Winter Olympics in the United States came from the abnormal climate. The sudden increase in temperature caused the ice and snow on the arena to melt. Many events could only be carried out in the thin residual snow, causing athletes to fall and bruise their faces. In the 1964 Winter Olympics in Innsbruck, Austria, because “everything is ready, except for snowfall”, in the warm winter not seen in 58 years, Austria urgently used the army to transport 20,000 cubic meters of snow from the top of the mountain to “rescue the field”. But before the opening ceremony, the field was damaged by rain again, and an Austrian skier and a British bobsleigher were killed in training. It can be seen that the key to the success or failure of the Winter Olympics is “cooperating with the weather”.

At the 1988 Calgary Winter Olympics in Canada, the smoky wind of 18°C ​​blew the ice and snow, causing the schedule to be delayed for 16 days and many events to be put on hold. But thanks to powerful artificial snow guns supporting the crisis, alpine skiing and the like can continue. Since the first use of artificial snow at the 1980 Lake Placid Winter Olympics, the Winter Olympics have begun to change the fate of being completely “depending on the weather”.

At 0°C, water in the atmosphere can crystallize into beautiful snowflakes with hexagonal outlines and symmetrical shapes, using tiny dusts as “condensation nuclei”. Artificial snowmaking is a rough simulation of the natural snowfall mechanism. After the water is fully atomized, it is sprayed into the cold air by a high-pressure pump and an exhaust fan, so that these tiny water droplets crystallize quickly. Scientists added a hydrophilic protein produced by bacterial fermentation as an ideal “condensation nucleus” to water, which not only made the water mist “fall into snow” faster and more completely, but also increased the crystallization temperature to 2°C to 2°C. 3°C. The “snow” ejected by the early “snow cannon” was actually tiny ice particles. With the development of science and technology, artificial snowmaking has become closer and closer to the natural snowflakes.

The Olympic Games applied artificial ice making technology much earlier. The 1908 London Olympics figure skating event was held on an artificial ice rink. In 1988, the Calgary Winter Olympics built a fully enclosed indoor speed skating stadium for the first time. Various artificial ice rinks can be seen everywhere in the world today. The refrigeration principle of artificial ice rink is similar to that of household refrigerator. We all know that under a standard atmospheric pressure, water will boil at 100 ℃ and absorb a lot of heat, and freon with a boiling point of -29.8 ℃ will also take away a lot of heat in the evaporator in the refrigerator, which will make the refrigerator refrigeration.

We might as well think of the artificial ice rink as an open, flat, enlarged refrigerator. The refrigerant that replaces Freon is often ammonia with a boiling point of -33.4 °C. The liquid ammonia under high pressure is sent to the dense pipes in the cement layer of the ice rink for vaporization, and then the removed heat is dissipated to the external environment. Can “freeze three feet”.

The actual process is naturally much more complicated. The “layer by layer” ice is painted from bottom to top into a white backing, and the clear site drawing lines and icon advertisements are spray-painted, and then 8-10 layers of thin ice tightly form a 4-centimeter-thick sports ice surface. Ice hockey requires a relatively “hard” ice rink, and the temperature of the ice surface should be -5°C, while for speed skating, the temperature of the ice surface should be between -2°C and -3°C. The heat load calculation, heat exchange control and daily maintenance management of the ice rink are all without special experts.

As for those “turned out” sled slides, they can also be regarded as elongated, curly, curved, and steep artificial ice rinks. The cement structure of the 1,600-meter slideway is covered with steel “peripheral blood vessels” from the bottom trough to the retaining wall. More than a thousand tons of ammonia water is like a magical “cold blood”, circulating along the “arteries” and “veins” extending from the central computer room. , to maintain the “body temperature” of this “Jade Dragon” -11 ℃. A computer network and dozens of sensors monitor the slides for minute changes at all times. Due to the huge and expensive construction, there are only a few artificial toboggan runs in the world.

The most impressive landscape is the super indoor ski resort in Dubai, a famous city in the United Arab Emirates. This “stove country” with a temperature of up to 60°C has never been able to get involved with ice and snow, but now it has an “ice and snow world” equivalent to the size of three football fields for more than a thousand people to skate and ski at the same time. The designer of “A Piece of Ice” relies on high-tech means to create the “Alps” in the hot desert.

Maybe we can build more artificial ice and snow fields that are “hot and cold around the world” one day, but as the “half the sky” of the Olympic Games, the Winter Olympics will probably only be held in winter in the high latitudes of the earth.

Our planet is beautiful and lovely because of the reincarnation of the four seasons, and the Winter Olympics is also a way for human beings to express their appreciation and gratitude to nature.

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