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Secret of Usain Bolt's speed unveieled
Scientists say they can explain Usain Bolt's extraordinary speed with a mathematical model.
His 100m time of 9.58 seconds during the 2009 World Championships in Berlin is the current world record.
They say their model explains the power and energy he had to expend to overcome drag caused by air resistance, made stronger by his frame of 6ft 5in.
Writing in the European Journal of Physics, the team hope to discover what makes extraordinary athletes so fast.
According to the mathematical model proposed, Bolt's time of 9.58 seconds in Berlin was achieved by reaching a speed of 12.2 metres per second, equivalent to about 27mph.
Less dynamicThe team calculated that Bolt's maximum power occurred when he was less than one second into the race and was only at half his maximum speed. This demonstrates the near immediate effect of drag, which is where air resistance slows moving objects.
They also discovered less than 8% of the energy his muscles produced was used for motion, with the rest absorbed by drag.
When comparing Bolt's body mass, the altitude of the track and the air temperature, they found out that his drag coefficient - which is a measure of the drag per unit area of mass - was actually less aerodynamic than that of the average man.
Effects of dragJorge Hernandez of the the National Autonomous University of Mexico said: "Our calculated drag coefficient highlights the outstanding ability of Bolt. He has been able to break several records despite not being as aerodynamic as a human can be.
"The enormous amount of work that Bolt developed in 2009, and the amount that was absorbed by drag, is truly extraordinary.
"It is so hard to break records nowadays, even by hundredths of a second, as the runners must act very powerfully against a tremendous force which increases massively with each bit of additional speed they are able to develop.
"This is all because of the 'physical barrier' imposed by the conditions on Earth. Of course, if Bolt were to run on a planet with a much less dense atmosphere, he could achieve records of fantastic proportions.
"The accurate recording of Bolt's position and speed during the race provided a splendid opportunity for us to study the effects of drag on a sprinter.
Bolt's time in Berlin was the biggest increase in the record since electronic timing was introduced in 1968.
Large strideJohn Barrow at Cambridge University who has previously analysed how Bolt could become even faster, explained that his speed came in part due his "extraordinary large stride length", despite having such an initial slow reaction time to the starting gun.
"He has lots of fast twitch muscle fibres that can respond quickly, coupled with his fast stride is what gives him such an extraordinary fast time."
He said Bolt has lots of scope to break his record if he responded faster at the start, ran with a slightly stronger tail-wind and at a higher altitude, where there was less drag.
Bolt's Berlin record was won with a tail wind of only 0.9m per second, which didn't give him "the advantage of helpful wind assistance", he added.
"You're allowed to have a wind no greater than 2m per second to count for record purposes, so without becoming any faster he has huge scope to improve," Prof Barrow told BBC News.
A huge cyclone that has forced as many as 500,000 people to flee their homes has made landfall in eastern India.
Winds were measured at 200 km/h (125mph) as Cyclone Phailin hit the coast near Gopalpur, Orissa state, at about 21:15 (15:45 GMT).
Authorities had predicted a storm surge of at least 3m (10ft) that was expected to cause extensive damage.
Officials say they are better prepared than in 1999 when a cyclone killed thousands of people in Orissa.
Cyclone Phailin has been classed as "very severe", and the head of India's Meteorological Office, LS Rathore, said it would remain in that category for six hours before losing strength.
At the scene
Andrew North BBC News, Orissa
As we arrived in Brahmapur, just inland from where the cyclone had first hit the coast, we were met with a scene of apocalyptic devastation.
The town was in total darkness, the headlights of our vehicle illuminating felled trees and power lines blocking roads.
Store signs and other debris were being pitched high in the air by powerful storm gusts. Elaborate decorations for a major Hindu festival that people were due to celebrate this weekend were strewn across the main road.
Most shops are shuttered, with hundreds of residents now evacuated. Many streets are already flooded, and this may be only the beginning as further heavy rain is expected.
The lobby of our hotel is now covered with glass, after several gusts blew in its main windows. It looks set to be a terrifying night, as the cyclone sweeps through this town and a vast swathe of the Indian coastline.
The eye of the storm was moving at 10-15 km/h (6-9mph), he said.
The BBC's Sanjoy Majumder reported heavy rain and high winds lashing Gopalpur as the cyclone made landfall.