Bending it like Beckham takes practice, physics
The British soccer player David Beckham is famous for many things. His hairstyles (there's a website that allows you to view yourself with 13 of his distinct do's); his fashion choices (the British tabloids just loved his male sarong and pink nail polish); and his marriage to a pop star, Victoria Beckham -- Posh Spice of the Spice Girls.
And then there's his soccer fame, which is largely based on his innate command of the laws of physics.
Beckham, who recently joined the Los Angeles Galaxy and will play against the New England Revolution Sunday at Gillette Stadium, is legendary for his ability to make a soccer ball curve and drop through the air. It is an ability that makes Beckham particularly dangerous on "free kick" situations -- when a player has been fouled and the referee awards his team an open kick where the key is to get the ball over and around a human wall formed by the opposing team in front of their goal. Beckham's skill is so impressive that it sent a team of international scientists into the lab to answer a question that soccer fans have long asked themselves: How do you bend it like Beckham?
Using wind tunnel experiments, high-speed video camera analysis, trajectory simulations, and computer modeling, scientists from the University of Sheffield in England and Yamagata University in Japan, along with specialists in computational fluid dynamics software at Fluent Inc. in New Hampshire, set out to determine how Beckham is able to achieve one of the most elegant effects in "the beautiful game" with nothing more than a foot tied into a soccer cleat.
The science of how a spinning object curves is nothing new, according to Matt Carré, the director of the sports engineering research group at the University of Sheffield and one of the lead researchers on the 2002 study. It's called the Magnus effect because it was first discovered in the mid-1800s by Heinrich Magnus, a German physicist who was studying the trajectory of cannonballs.
Carré said that as soon as a ball starts spinning, the air pressure becomes greater on one side than the other, creating a nonsymmetrical drag on the ball that results in a side force that makes it curve.
But he and his team wanted to figure out how Beckham was able to not only make it curve, but rise up over the human wall and then down again so that it doesn't fly over the net.
"What we found is that he kicks to one side of the ball to give it some sidespin and make it curve, but he's able to effectively wrap his foot around it to also give it some topspin to go up and down," he said. "He's very unique in the way he's able to caress the ball with his foot. It's almost like he's stroking the ball in the way a tennis player would."
Carré said his study was triggered by a particular Beckham kick on Oct. 6, 2001. The English national team needed to at least tie Greece to qualify outright for the 2002 World Cup. Late in the game, England was losing 2-1 when one of their players was fouled just outside the Greek penalty area. With time running out on the clock, the referee awarded a free kick, and Beckham addressed the ball.
What happened next is the "stuff of folklore," according to Carré. With four Greek players forming a human wall in front of their goaltender, Beckham ran up to the ball, planted his left foot and fired a kick with his right foot that appeared to head directly for the head of the defender on the left side of the wall. Just as the defender jumped to head the ball away, the ball rose and curved to the left as it passed the wall, before dipping back down as it traveled just inside the top left corner of the net, leaving the Greek goalkeeper stunned.
Carré said that while there are several players who are well known for their ability to curve a ball on a free kick -- including Beckham's former Real Madrid teammate, Roberto Carlos of Brazil -- what sets Beckham apart is his control and consistency.
But with the study complete, the question remains: is this something that can be learned and copied? Carré is not sure, and uses an analogy to the golfer Tiger Woods. While we may be able to see and study how Woods hits a golf ball, he says, are we able to replicate it?
"I think it's partly due to [Beckham's] anatomy," Carré said. "To get his right foot into the proper position, his left foot is planted in a very contorted, awkward position. But we know he did practice this over and over when he was a young footballer, the way Tiger Woods practiced putting backspin on a golf ball. It's a very deliberate technique."
Still, says Carré, it doesn't always work, even for Beckham.
"He has been known to fall over," he says. 