Great article from yesterday’s Sunday Times about the Science behind Ronaldo’s 40 yard screamer on Wednesday vs Porto. We’ll do a few more Sports-related articles over the next few days, starting with the Science behind Tim Wakefield’s timeless knuckleball-pitch in baseball.

-Brian

Science behind wonder strikes
The key to Ronaldo’s shooting prowess is a lack of spin on the ball
Matthew Fearon
THE speculation arrived almost as swiftly as Cristiano Ronaldo’s brilliant goal hit the net against Porto last week. Does the Portuguese really have the hardest shot in football? One sports scientist suggests the pundits are asking the wrong question. Ronaldo may not have the most powerful shot in football but it could well be the best.

Graphic image of the strike

Dr Andy Harland says Ronaldo’s 39-yard strike had very little to do with power and everything to do with his manipulation of the laws of physics. Recent experiments in football design technology show that modern-day footballs lose between 30% and 40% of their speed shortly after impact. Harland argues that the key for any footballer is to make sure your strike loses less speed than everybody else’s, which is where Ronaldo’s unique approach raises him above the crowd of pretenders. “Every time a ball rotates through the air it creates drag and slows down, so the more spin a player places on the ball the more speed his shot will lose in flight,” says Harland, a senior member of Loughborough University’s sports technology research group and part of the team that developed the official ball for the 2004 European championship.

Great picture showing the technique involved

“Ronaldo’s aim when he strikes the ball, whether he’s aware of it or not, is to eliminate as much spin as possible and then leave the fate of the ball to nature’s randomness.”

Harland treats with scepticism some of the technology used to measure the speed of shots - Sky Sports’ digital replay system, derived from Israeli missile technology, clocked Ronaldo’s strike at 64.2mph. “The problem lies in the fact that speed guns measure velocity over a given distance but any variable in the positioning of the gun relative to the flight of the ball will alter the results.”

He also dismisses the suggestion that football’s hardest shot of all time was Ronny Heberson’s 132mph strike for Sporting Lisbon against Naval in 2006. “It’s just not possible to hit the ball at 132mph,” says Harland. “When we conducted studies across training grounds, the hardest anyone hit the ball was in the high-80mph zone. Ronaldo’s technique is such that it allows him to make the ball go faster for far longer than any of his rivals.” According to Harland, David Beckham’s technique is as unique as Ronaldo’s but exists at the other end of the spin spectrum. “Beckham’s trick is to alter the ball’s axis of spin. His exaggerated leaning-body position on impact alters the axis rather than generating more rotations, which all means he is able to introduce a swerve and dip to his free kicks and shots that compensates for any loss of velocity.”

A common suggestion as to why modern balls move more than their predecessors from yesteryear is that they are lighter, but Harland dismisses this. “The first myth to debunk is the one that the new balls are lighter,” he says. “Each tournament this is a common quote from the players, but Fifa closely regulate the density of the balls and it hasn’t changed for a long time. Ahead of the 2006 World Cup, we conducted an experiment using our ball-striking simulator with a 1970 hand-stitched leather ball, a ball used during the 2001-02 Premier League season and the 2006 World Cup ball. The results showed there was less than a 1mph differential.”

As for the World Cup in South Africa next year, Harland notes that the variations in altitude of venues will affect the speed that the ball travels through the air. However, with Portugal far from certain to qualify, Ronaldo might not be able to take advantage.