Scientists uncover physics of “impossible” Roberto Carlos shot

In lieu of a column this week, watch the amazing video:

Then read the AP story:

PARIS (AP) — Thirteen years after Roberto Carlos stunned onlookers with his amazing “banana” free kick that seemed to defy the law of physics, scientists finally have figured out just how he did it.

In what many people regard as the best free kick in the history of the game, the Brazil
defender struck the ball with the outside of his left foot from 35 yards away, bending it
around the outside of France’s three-man wall during an exhibition tournament in Lyon in 1997.

The ball looked way off target to the right — a ball boy standing 10 yards from the goal
even ducked his head — but at the last moment, it swerved dramatically inside the post and into the net. The bewildered France goalkeeper, Fabien Barthez, had not even moved.

Many people thought the shot was a fluke, but researchers say it can all be explained by science.

“What happened that day was so special,” researcher David Quere told The Associated Press. “We are confronted with an unexpected law of physics, but it’s possible to see this again.”

Quere, a physicist at the ESPCI and Ecole Polytechnique in Paris, and his colleagues have developed an equation to explain the bizarre trajectory of the shot. Using a small
pistol to fire bullets into water at the speed of more than 60 mph — approximately the speed of Roberto Carlos’ shot — they discovered that the path of a sphere when it spins is actually a spiral.

Quere said the study, which has been published in the New Journal of Physics, confirmed the “Magnus effect” — which is responsible for the curved motion of a spinning ball — but it also revealed what the scientists call the “spinning ball spiral.”

The spiral effect appears after about 40 yards with a soccer ball. As the ball slows, the
“Magnus effect” becomes increasingly pronounced, which eventually creates a spiral.

“The crucial thing is that while the ball is slowing down, the rotation is the same,” Quere said. “Hence the trajectory of the ball is going to be more and more bent, that is what creates the spiral.

“When Michel Platini or David Beckham were kicking free kicks from 20 yards, they were bending the ball in an arc. It’s not the same thing with Roberto Carlos’ goal. He can have this kind of effect because he kicks from long range.

“Another player could repeat it — on the condition that the ball is kicked hard enough, that the kick is taken from about 40 yards and that the player gives some effect to the ball.”

Roberto Carlos claimed at the time he had done it all before, against Roma when he was playing for Inter Milan, although he never quite managed to repeat his 1997 trick.

“It’s difficult to say whether it was a lucky goal,” Quere said. “There is something close to perfection in this trajectory that let me think that Roberto Carlos has probably always taken these kinds of free kicks from long range, and he should have realized that he could take advantage of it.”

Barthez said after conceding the goal that he didn’t set his wall correctly, but Quere said the goalkeeper probably just thought Roberto Carlos had flubbed his shot.

“Barthez was a very good keeper, at the peak of his art,” Quere said. “But the trajectory was eccentric and he didn’t move.”

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  • Studs Up

    Ricketts could have save that based on his last performance. :-D

    Roberto Rivelino had done even better. Best lefty in my book (don’t tell Maradona).

  • Soccer Fan

    Nick,

    Are the Galaxy going to have a final bonus game as planned this season? Have you heard who it might be? I would assume it will not be a European team unfortunately.

    Thanks

  • Inigo Montoya

    No disrespect to Roberto Carlos, but DeRo’s free-kick goal against the Galaxy in 2005 is the one I remember. A sharp left hook around a well-placed wall from 30 yards, still rising when it beat Hartman and hit the roof of the net.

    http://www.youtube.com/watch?v=ML7Kh_Na3Tg

  • Artman

    I agree with DeRosario’s kick being better. It is just physics. Both of those kicks are basically a screwball in baseball, maybe a hard a fastball with a 8-2 spin that cuts back. Beckham’s free kicks are curveballs, sometimes sliders if hit hard enough, also like a 1-7 or 2-8 spin (on a clock). Any player can kick a knuckleball, just hit is so there is no spin, thus no stability, not predictable, ball just travels to area of least pressure on its travels. Ronaldo’s kicks are like a split finger fastball or spitball, ball has very little spin, maybe 3 or 4 rotations downward and dips at the last moment. One of the best goal scoring kicks are the top spin volleys. Hit it off the bounce and put a hard straight downward spin like a 12-6 curveball, these will pass over the outstretched keeper dip right under the crossbar. And then there is the dreaded backspin rising fastball kick that just keeps rising and sails over the crossbar 30 yards into the crowd!

  • PABLITO

    Inigo / Artman – you guys are CRAZY!!!

    Roberto’s kick was 10x more phenomenal. It’s been almost 15 years since that kick and the whole world knows it as the greatest ever.

    MLS homers.

  • http://www.insidesocal.com/soccer Nick Green

    I have not heard of another exhibition game being planned; I will check and let you know.