How a ski-jumper learns to fly?



When the 18-year-old Austrian Sepp Bradl became the first person to ski-jump more than 100m (328ft) in 1936, the engineer who had designed the jump - in Planica, Yugoslavia - shouted: ‘That was not ski-jumping. That was ski-flying!’



It was true. A new sport had been born, in which the skiers had to develop a totally new skill, turning themselves into aerofoils. Their ability to win now depends less on jumping than on flying. As he glides through the air, the skier leans forward with his body slightly curved. The same aerodynamic forces that keep an aeroplane flying help the ski-jumper to remain in the air longer and travel farther. The air passes over his curved back faster than under his front, creating a partial vacuum which causes lift.



Since Bradl’s 100m jump, the world record has been almost doubled, to 180 m (590ft) in 1989.



Sky jumpers start learning at practically any age. First, the jumper learns how to build up speed. This is done on a normal ski slope. The skier crouches down in a position that minimises air resistance, with the arms are swept back. World-class jumpers take off at up to 60mph (100km/h).



Before making his first real jump, in the skier must know how to land. He learns to touch down with 1 foot slightly in front of the other, and the knees bent.



Fledgling skiers buildup experience by making small jumps from low banks or platforms. This teaches them to cope with the takeoff. If balance is wrong on take off - in particular, if the weight is too far back - wind will flip the jumper over.



The true glory of ski-jumping is the flight itself. The beginner‘s first real jump will probably carry him about 10 m (30ft). Only when they become teenagers are most children able to make jumps of 40 m (130ft), for which they must adopt the true aerofoil position.



The flight itself is a complex operation. As he loses his horizontal motion, the jumper contracts his body a little, ready to meet the slope beneath him. As he falls, he loses speed but bends forward, and with skill can extend his glide.



In-flight, perhaps the greatest danger of all comes from wind. However, although injuries happen, fatalities are there.



 



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What is the purpose of the land diving or Naghol ritual on the Pentecost Island in the South Pacific?



High above the hillside in a jungle clearing, the man balances precariously on two planks projecting from the top of 100 feet 30 m rickety looking wooden Tower. Spectators hold their breath.



Suddenly the man tosses a spray of leaves in the air. As it spirals down, he leans slowly forward and falls head first after it in a spectacular dive. But just as it seems his head is about to strike the ground, he is jerked up again into an arc which swings him to a safe landing on the hillside.



For both the man’s ankles are tied with the lianas - tough jungle vines - tethered to the top of the tower. The death-defying dive is the climax to an annual ceremony called the Naghol or Gol. It is held on Pentecost, one of 80 islands of the pacific republic of Vanuatu - until 1980 the New Hebrides.



The ritual features many diverse leaping from progressively higher platforms, the lowest around 40 ft (12 m).



Why do the Pentecost islanders risk their lives in such a bizarre and dangerous way?



The true origin of the Gol is unknown, but the participants see it as a test of courage the closer they swoop to the ground, the greater their bravery.



The ceremony has Ali Diwali Hai safety record, but sometimes it goes wrong. In 1974, one diver’s lianas snapped as they were jerked taut and he was killed. The ceremony was witnessed by the Queen and other members of the British royal family.



The tower is a flexible structure of palm trunks and bamboo, constructed around the living tree, stripped of most of its branches. The lianas that tether the divers are the real key to safety, however. They must be the right age and diameter and are cut two days before the ceremony. If they were cut earlier, they could try out, become brittle and lose the elasticity. They are also carefully cut to suit the height from which each diver plans to fall. The cutting is done by an experienced man who can calculate the elasticity of the vines.



Although the Gol’s origin is lost, a legend tells that the first driver was a woman. Her husband, discovering she was being unfaithful, chased her, intending to beat her. She climbed a tall palm, but he scrambled up after her. At the top he demanded to know why she had been unfaithful. She replied that he was a coward and dared him to jump in with her from the tree top. The husband agreed. They jumped. The man was killed, but his wife had surreptitiously tied a vine to her ankle to break her fall.



 



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What is the barefoot walking over red hot stones?



Silently, the file of barefoot men and boys the oldest nearly 60, the youngest eight emerged from the hut. Still in silence they walked to a pit full of stones, where a log fire had been burning for many hours. The embers had been raked away, but heat haze still shimmered over the pit. Without a pause they walked and unhurriedly across the stones and out the other side. The temperature in the pit was about 1200°F (650°C). Yet their feet were unharmed.



It is a feat often performed on the Fijian Island of Mbengga, whose firewalkers are world-famous. Similarly rituals are practised in India and Sri Lanka and by the Greeks sect of Anastenaria. They have been reported in South America and Suriname, and the tiny Pacific island of Rarotonga. In Hawaii, hot lava has been used instead of stones or hot coals. Firewalking has also taken place in the USA and Europe.



In Fiji, India, Sri Lanka and Greece the ritual is associated with the religious ceremonial. Fire walkers of the western world usually prepare by psychological training. All maintained that a particular state of mind is the key to the remaining unharmed. Unlucky aspirants who suffer burns are often deemed to be mentally unprepared.



In Fiji, preparation includes avoiding the company of women during the days beforehand, and no firewalker should try it if his wife is pregnant.



Scientists tend to discount the ‘mind over matter’ theory. They suggest that walking over damp grass beforehand, which some fire walkers do, provides temporary protection through a phenomenon that accounts for the surprising amount of time that a drop of water bounces over a hot griddle before evaporating. The bottom of the drop vaporises providing a brief insulation of vapour between the drop and the griddle. The dampness of a fire walkers feet could have a similar effect.



Scientist also think the stones used in Fiji and elsewhere - and the coal is used in the West - give off heat relatively slowly.



But most are convinced that, whatever the reason for the fire walkers apparent immunity, it can be dangerous.



 



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What are the Weapons like wooden swords?



The first white man to describe an Aboriginal boomerang was Sir Joseph Banks, the English naturalist who was a member of Captain cooks landing party in South East Australia on April 29, 1770. Among the reception party at Botany Bay were two natives who eyed the explorers with suspicion.



‘Each of these held in his hand a wooden weapon about 2.5 feet long, in shape much resembling on scymeter (scimitar),’ wrote Sir Joseph. ‘The blades of these looked... smeared over with the same white pigment with which they painted their bodies.’



The explorers regarding the weapons as no more than what Captain Cook called ‘wooden swords’. Then, in the early 1830s, another naval officer - Lieut WH Breton - became the first person to record an Aborigine throwing one of the banana shaped objects. It moved in ‘a very considerable curve,’ he stated, to ‘finally, fall at his feet.’



Boomerangs are made from hardwoods such as black wattle and sandalwood. They are sometimes coated in red ochre - and, for ritual use, are decorated with red, yellow and white.



As well as for killing game, Aborigines used them for cutting open the bellies of dead animals, for clearing fire sites, digging cooking pits, and unearthing honey ants. Sometimes they were used for lightning fires, by rubbing them against logs. And they were banged together to beat out the rhythm of a dance.



 



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How to do dimples created Maarten golf?



The dimples that cover the surface of golf balls revolutionised the game when they were introduced the century. A well driven modern golf ball and travel up to 300yds (275 m). If it were smooth, it would only travel about 70yds (65 m).



When golf was first played in Holland and Scotland in the 15th century, smooth leather balls stuffed with feathers were used. In the 19th century, balls made of rubbery substance called gutta-percha were introduced. They were found to fly farther after being marked my club blows.



Makers began pattering balls with crisscrossed grooves. Then, in 1906, when rubber cored balls had arrived, the first dimpled ball was produced.



Why do Dimples help the ball to go so far? When a ball is in flight, a thin layer of air clings to its surface at the front. As the air passes over the ball, it breaks away from the surface, setting up turbulent eddies behind. The eddying air draws its energy from the ball, slowing it down. Dimples cause the air to cling to the surface until it is well towards the rear of the ball. When it finally breaks away, and narrower stream of turbulence is created, causing less drag than for a smooth ball.



The Dimples have another purpose as well. Since the golf ball always spins backwards when it is struck, the dimples carry air upwards over the top. The air going over-the-top has to travel faster than the air going underneath because of this rotation. This creates a lower pressure above than below, so the ball experiences lift which keeps it in the air longer.



 



Picture Credit : Google