Category: physics

Curling is a deceptively engrossing sport with…

Curling is a deceptively engrossing sport with some unique physics among Winter Olympic events. Athletes slide 19kg granite stones at a target 28 meters away. Along the way, teammates sweep the pebbled ice with brooms, melting it with frictional heating to help the stone slide further. The underside of the stones is concave, so they only touch the ice along a narrow ring. Researchers think roughness in the leading edge of the sliding stone cuts into the ice, leaving scratches that the trailing edge tries to follow. This is what causes the stone’s trajectory to curl. By melting the ice, sweeping also prevents curling, so competitors must know exactly when and how much to sweep. Ice conditions shift throughout a match, and the best players can read the ice to keep their stones where they want them. (Image credit: AP; W. Zhao/GettyImages)

Cross-country skiing, also known as Nordic ski…

Cross-country skiing, also known as Nordic skiing, is a part of many longstanding disciplines in the Winter Games. Unlike downhill skiing, cross-country events typically involve mass starts, which allow athletes to interact, using one another for pacing and tactics. Drafting can be a valuable method to save energy and reduce drag. A following skier sees a 25% drag reduction while drafting; the lead skier gets about a 3% reduction in drag compared to skiing solo. Competitors usually wear tight-fitting suits to minimize drag, but unlike speedskating, for example, cross-country skiers don’t get much benefit from roughened surfaces and impermeable fabrics. Typical race speeds are 4 – 9 m/s, and most of these high-tech fabrics don’t provide tangible benefits until higher speeds. (Image credit: Reuters/S. Karpukhin, US Biathlon, GettyImages/Q. Rooney)

When it comes to winter sports, not all ice is…

When it comes to winter sports, not all ice is created equal. Every discipline has its own standards for the ideal temperature and density of ice, which makes venue construction and maintenance a special challenge. Figure skating, for example, requires softer ice to cushion athletes’ landings, whereas short-track speed skating values dense, smooth ice for racing. The Gangneung Ice Arena hosts both and can transition between them in under 3 hours. Gangneung Oval hosts long-track speed skating and makes its ice layer by layer, spraying hot, purified water onto the rink. This builds up a particularly dense and therefore smooth ice. 

The toughest sport in terms of ice conditions is curling, which requires a finely pebbled ice surface for the stones to slide on. Forming those tiny crystals on the ice sheet can only be done at precise temperature and humidity conditions. This is a particular challenge for Gangneung Curling Center due to its coastal location. To keep the temperature and humidity under control at full crowd capacity, officials even went so far as to replace all the lighting at the facility with LEDs! (Image credit: Pyeongchang 2018, 1, 2, 3)

In bobsleigh, two- and four-person teams compe…

In bobsleigh, two- and four-person teams compete across four runs down an ice track. The shortest cumulative time wins, and since typical runs are separated by hundredths of a second, teams look for any advantage that helps them shave time. The size, weight, and components of a sled are restricted by federation rules; for example, teams cannot use vortex generators to improve their aerodynamics. Instead bobsledders work with companies like BMW, McLaren, and Ferrari to engineer their sleds. Both computational fluid dynamics and wind tunnel tests with the actual team in the sled are used to make each sled as aerodynamic as possible. (Image credit: IOC, Gillette World Sports, source)

These days artificial snow-making is a standar…

These days artificial snow-making is a standard practice for ski resorts, allowing them to jump-start the early part of the season. Snow guns continuously spray a mixture of cold water and particulates 5 or more meters in the air to generate artificial snow. The tiny droplet size helps the water freeze faster and the particles provide nucleation sites for snow crystals to form. As with natural snow, the shape and consistency of the snow depends on humidity and temperature conditions. Pyeongchang is generally cold and dry, so even the artificial snow there tends to be similar to snow in the Colorado Rockies. Recreational skiers tend to look down on artificial snow, but Olympic course designers actually prefer it. With artificial snow, they can control every aspect of an alpine course. For them, natural snowfall is a disruption that puts their design at risk. (Video credit: Reactions/American Chemical Society)

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drnikolatesla:

“Nikola Tesla For The First Time Describes His New System For Supplying Wireless Power To Run All The Earth’s Industries.”

By a series of discoveries and inventions just perfected, Nikola Tesla, the electrical scientist, has upset what has hitherto been regarded as one of the fixed laws of nature. “Every effect diminishes with distance,” is the way the textbooks have expressed it. Tesla now says that instead of decreasing like other forces, electricity may be made to increase in intensity with the distance traveled.

The full significance of this discovery may not be at once apparent. It is obvious, however, that it annihilates space. There can be no limit to the power of the electric wave which increases in intensity the further it travels.

For nearly 20 years Tesla has been working on his plan, he calls it his wireless “World System.” If it is put into successful execution it will convert the earth into a gigantic conduit, which will pass power for all earthly activities, and make possible communication with other planets.

From time to time Tesla has made partial announcements as his work progressed. This, however, is the first comprehensive account of his system as a whole that the inventor has consented to give to the world.

“Through ages past man has always attempted to project in some way or other energy into space. In all his attempts, no matter what agent he employed, he was hampered by the inexorable law of nature which says every effect diminishes with distance, generally as the square of the same, sometimes more rapidly.

“I saw at once that space was annihilated in all the three aspects; in the transport of our bodies and materials and in the earth, transmission of the energies necessary for our existence. You can imagine how profoundly I was affected by this revelation. Technically, it meant that the earth, as a whole, had certain periods of vibrations, and that by by impressing electrical vibrations of the same periods upon it, it could be thrown into oscillations of such nature that innumerable benefits could be derived.

“It is difficult to convey an idea of these inventions without resorting to technical terms. The first and best known of these is my transformer, which enables the production of electrical vibrations of transcending intensities. I have already attained activities of many millions of horse power; but this is nothing compared to those which I am expecting to get with my improved apparatus.

“The second is what I have termed my magnifying transmitter, which I look upon as my best electrical invention, and with which any distance can be bridged. I have already passed of this wonderful instrument and am confident that a message can be flashed to such a distance as the planet Mars.

“Some technical men would be disposed to look upon such statements as those of a dreamer, but it is only because they have not had opportunities to see experiments which I have actually performed. The third invention I have designated as the “Art of individualization,” which enables the transmission of an unlimited number of messages through a wire or wireless, without the slightest interference. Not before this improvement is universally adopted will the world fully realise the benefits of telegraphy and telephony. The fourth invention is my receiver, which concentrates the energy transmitted over a wide area into the operating device.”

What would the voltage in your transmitter be?

“In the transmission of telegraphic and telephonic messages I shall employ from five to ten million volts, but in transmitting power in great quantities, as much as one hundred million volts will be used.“

How will your “World System” compare with those now in use as regards to cost?

“We could easily afford to offer a transmission of telegraphic and telephonic messages to any terrestrial distance for five cents a word. In a short while no one will think it anything out of the way to dictate or to write a long letter across the Pacific.”

How long does it take for the transmission of a message, by your system, around the world?

“The exact time is, according to my measurements, 43-1000 of a second, which is a speed about 50 per cent greater than that of light.

“The impulse starts from my magnifying transmitter with infinite speed, slows first rapidly and then at a lesser rate until, when it has penetrated to a distance of 6000 miles from the transmitter, it proceeds with approximately the speed of light. From there on it accelerates, first slowly and then more rapidly, and reaches the opposite point of the globe again with infinite speed only to rebound and pass through the same phases on its way back to the transmitter.

“This movement of electricity through the Earth, which takes place strictly in accordance with a mathematical law, and enables a great number of accurate measurements and determinations to be made, which are of immense practical and scientific value.”

Is your universal marine service based upon this principle?

“Largely so. In setting up and maintaining stationary waves in the earth its entire surface is subdivided in perfectly definite zones of electric activity, so that any observer of all those data which are of importance to navigators as the latitude and longitude, the position with reference to a given point, the speed of travel, and the course followed. This method is quite exact and reliable, and once introduced will be instrumental in a great saving of time, life and property.”

When your system of time distribution is introduced what kind of devices will be used for indicating the hour?

“They will be ever so much simpler than the ordinary clocks or watches, being entirely devoid of wheel work. For personal use a small case will be provided resembling that of a watch which would indicate precisely the time and require no more attention than a compass for instance. The large clocks on towers and public edifices in general will be replaced by extremely simple devices operated on the same principle.

“All these will be ‘tuned’ to a wireless wave sent out at a certain time. This will automatically set the hands of every ‘tuned’ time piece.”

In operating stock tickers, will the present instruments have to be replaced by others?

“Not at all, they will remain intact. A great financier told me that this should be one of the most valuable and practical applications of my system, inasmuch as the instantaneous operation of such instruments all the world over will go far toward allaying panics and failures which are at present mostly due to the inadequacy and stagnation of channels of information.”

“A business man will be able to dictate in his office a letter which will appear in type at any other place he wishes without loss of time in the transmission. It will be exactly as though he had his stenographer close by. In the same manner it will be practicable to send a handwritten letter or even a check, and what is more important, it will not be possible to falsify the signature.”

Will the transmission of complex musical productions require complicated apparatuses?

“Not at all. The apparatus at any of the master plants, transmitting a great number of musical compositions, will be of necessity complicated, but the subscriber will need only a telephone receiver, and, if he desires exclusiveness, and individualizing device in connection, which, however, will be rarely required. He will be none the less able to listen to the most complex opera played in some remote party of the world. What is more, he can carry the entire outfit with him on his walks and travels, and whenever he desires to listen to the music he can do so.

“The wireless system which I have developed does not contemplate competition with established lighting systems in densely populated districts, but it offers an ideal solution for the illumination of isolated places. The light will be furnished by exhausted glass tubes, bent in all sorts of ornamental shapes, and is of surpassing beauty, resembling closely the daylight. The lamps will last forever. The entire apparatus for lighting the average country dwelling will contain no moving part whatever, and could be readily carried about in a small valise. It will be quite immaterial in which region of the earth the house to be lighted is located. Distance will not affect the charge.“

How far from the Earth’s surface can power be transmitted by this wireless system?

“To any distance; in fact, the greater the elevation above the ground the easier it is to supply the power to the vehicle, such as an airship crossing the ocean.”

What do you consider the most important application of your system?

"The transmission of power, of course. The operation of aerial machines alone will be of a revolutionizing influence, in as much as it will afford a perfect solution of this important problem.

"Another great field will be the irrigation and fertilization of the soil by wireless power. The time is not distance when a farmer will have installed on his place an apparatus for continuously manufacturing, from the gases of the atmosphere, nitric compounds which will be used to fertilize, while a motor will pump the water and perform other duties; all the energy being supplied from a plant perhaps thousands of miles away. This system can be extended so as to make productive vast tracts of now barren lands located in various countries. I believe that the export of wireless power will be one of the chief resources of the United States and other fortunately situated countries in times to come.“

By Marcel Roland. New York American, September 3, 1911.

Four years ago in Sochi, Under Armour’s suits …

Four years ago in Sochi, Under Armour’s suits for the U.S. speedskating team took a lot of flak after the team failed to medal. The company defended the physics and engineering of their suits, and an internal audit of the speedskating program ultimately placed blame on flaws in their training regimen, unfamiliarity with the new suits, and overconfidence.

This time around Under Armour has taken a more hands-on approach with the team, helping with training regimens in addition to providing suits. Under Armour spent hundreds of hours testing the suits in Specialized’s wind tunnel, including testing many fabrics before settling on the slightly rough H1 fabric used in patches on the skater’s arms and legs. Like the previous suit’s dimpled design, the roughness of the fabric promotes turbulent flow near it. Because turbulent flow follows curved contours better than laminar flow does, air stays attached to the athlete for longer, thereby reducing their drag. The suit is also designed with asymmetric seams that help the athlete stay low and comfortable in the sport’s frequent left turns.

U.S. speedskaters have been competing in a version of the suits since last winter, ensuring that athletes are familiar with the equipment this time around. Whether the new suits and training program will pay off remains to be seen. After their disastrous experience in Sochi, both the team and the company are shy about setting expectations. (Image credits: D. Maloney/Wired; US Speedskating)

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drnikolatesla:

🔥Nikola Tesla Roasts the Pop Science World

ASKED to select his choice of the greatest modern and future wonders, the electrical wizard refused to accept the popular notion of what is wonderful. His reply led him into onslaught on the scientists who have abandoned “cause and effect” and who take the position that there are accidents in nature and that anything might happen.

“To the popular mind, any manifestation resulting from any cause will appear wonderful if there is no perceptible connection between cause and effect. For instance, through the means of wireless telephone speech is carried to opposite points of the globe. To the vast majority this must appear miraculous. To the expert who is familiar with the apparatus and sees it in his mind’s eye the result is obvious. It is exactly as though visible means existed to which the impetus is transmitted.

“As I revolve in my mind the thoughts in answer to your question I find the most wonderful thing is the utter aberration of the scientific mind during the last twenty five years. In that time the relativity theory [(Albert Einstein)], the electron theory [(J. J. Thomson)], the quantum theory [(Max Planck, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, Arthur Compton, Paul Dirac, Wolfgang Pauli)], the theory of radioactivity [Marie Curie] and others have been worked out and developed to an amazing degree. And yet probably not less than 90 per cent of what is thought today to be demonstrable scientific truth is nothing but unrealizable dreams.

“What is ‘thought’ in relativity, for example, is not science, but some kind of metaphysics based on abstract mathematical principles and conceptions which will be forever incomprehensible to beings like ourselves whose whole knowledge is derived from a three-dimensional world.

“The idea of the atom being formed of electrons and protons which go whirling round each other like a miniature sun and planets is an invention of the imagination, and has no relation to the real nature of matter.

“Virtually all progress has been achieved by physicists, discoverers and inventors; in short, devotees of the science which [Isaac] Newton and his disciples have been and are propounding.

“Personally, it is only efforts in this direction which have claimed my energies. Similar remarks might be made with respect to other modern developments of thought. Take, for example, the electron theory. Perhaps no other has given rise to so many erroneous ideas and chimerical hopes. Everybody speaks of electrons as something entirely definite and real. Still, the fact is that nobody has isolated it and nobody has measured its charge. Nor does anybody know what it really is.

“In order to explain the observed phenomena, atomic structures have been imagined [(Quantum Mechanics)], none of which can possibly exist. But the worst illusion to which modern thought has led is the idea of ‘indeterminacy’ [(ex. Uncertainty Principle: W. Heisenberg, E. Schrödinger)]. To make this clear, I may remark that heretofore we have in positive science assumed that every effect is the result of a preceding cause.

“As far as I am concerned, I can say that after years of concentrated thought and investigation there is no truth in nature of which I would be more fully convinced. But the new theories of ‘indeterminacy’ state this is not true, that an effect cannot be predicted in advance.

“If two planets collide at certain time and certain place, this is to the student of positive science an inevitable result of preceding interactions between the bodies; and if our knowledge would be adequate, we would be able to foretell the event accurately.

“But in the spirit of the new theories this would simply be an accident. ‘Indeterminacy’ introduces into the world of inert matter a principle which might virtually be compared with the universal illusion of free will.

“Of course, there is no such thing. In years of experimenting I have found that every thought I conceive, every act I perform, is the result of external impressions on my senses.

“It is only because the vast majority of human being are not observant sufficiently that they live in the illusion of perfect choice and freedom in their thoughts and actions. And if this holds true even in the most complex and involved manifestations of human life, it holds true with the same force in all the world of matter.”

–Nikola Tesla

“Great Scientific Discovery Impends.“ The Sunday Star, Washington D.C., May 17, 1931.

Skeleton, the sliding event in which athletes …

Skeleton, the sliding event in which athletes race down an ice track head first, is a fast-paced and punishing sport. Skeleton racers can reach speeds of 125 kph (~80 mph) during their descents. This is a little slower than the feet-first luge, in part because the skeleton sled runs on circular bars rather than sharp runners. 

Body positioning is key in the sport. It’s the athlete’s primary method of steering, and it controls how much drag slows them down. But skeleton runs are brutally taxing; athletes pull 4 or 5g in the turns – more than astronauts experience during a launch! All that jostling means athletes cannot stand more than about 3 trips down the track in a day. To practice positioning without the bone-jarring descent, athletes can work in a wind tunnel. While the wind tunnel provides the aerodynamic equivalent of their usual speed, athletes focus on holding their bodies in the most streamlined position. Some wind tunnels are even able to provide screens that let the athletes see their drag values in real-time, letting them adjust to learn what works best for them. (Image credit: N. Pisarenko/AP, Bromley Sports)

No winter sport is more aerodynamically demand…

No winter sport is more aerodynamically demanding than ski jumping. A jump consists of four parts: the in-run, take-off, flight, and landing. The in-run is where an athlete gains her speed, and to keep drag from slowing her down, she descends in a streamlined tuck that minimizes frontal area. The biggest aerodynamic challenge comes during flight, when the jumper wants to maximize lift while minimizing drag. The athlete spreads her skis in a V-shape and flattens her body, using her hands to adjust her flight. Flying the farthest requires careful management of forces while in the air. Wind plays a major role as well, with headwinds helping athletes fly farther. To compensate, scoring includes a wind factor calculated based on conditions for each jump. (Image credit: B. Pieper, Reuters/K. Pfaffenbach, PyeongChang 2018)