World Cup soccer ball travels faster and farther at high altitudes
World Cup soccer balls will travel faster and straighter through Johannesburg's thin air, a NASA scientists has warned.
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Mehta also did some research on the aerodynamics of the new soccer ball being used at the 2010 World Cup. For the competition Adidas introduced a new ball called Jabulani (Zulu for "celebration"). The new model is made out of eight panels, compared with the previous 14, and has special aerodynamic ridges on its surface.Skip to next paragraph
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The ball is an adjustment to a previous new ball called Teamgeist, introduced for the last World Cup in 2006. At the time, Adidas said it was the world's most accurate soccer ball, though players complained it didn't perform as they were used to.
Mehta said Jabulani will probably have some of the same quirks as Teamgeist.
A primary issue is what's called "knuckle-balling." A knuckle ball is a ball that swerves or veers in unexpected directions. This happens because the ball is kicked straight, without spin.
Ironically, that lack of spin on the ball causes its path to curve because of aerodynamics. The ball is not perfectly smooth because of the seams between its panels, and now because of the added ridges. These irregularities cause an asymmetric flow of air around the ball, creating side forces that push the ball into a swerve.
The new ridges and overall design make Jabulani even easier to knuckle-ball at the speeds commonly kicked at during free-kick around the goal area.
Knuckle-balling is not necessarily bad – sometimes it helps throw the goalie off if a ball swoops at the last minute. But players like being able to anticipate where their kick will land, and the new ball will take some adjustment, Mehta said.
Mehta shared some of these findings with a group of students who were invited to test out the new ball at an event held by NASA Ames's Fluid Mechanics Laboratory.
"It's amazing how kids get excited when you start talking about sports," Mehta said. "All these efforts are meant to get kids more interested in science and engineering."
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