World Cup soccer balls will travel faster and straighter through Johannesburg's thin air, a NASA scientists has warned.
World Cup players might notice some strange things happening to their kicks because of the peculiar aerodynamics of playing soccer at the high altitude of the Johannesburg, South Africa, stadium, a NASA scientist warned today.
At altitude, the air pressure is lower, and so are aerodynamic effects such as drag and lift, ultimately causing balls to travel faster and straighter than they would at lower altitude. Johannesburg is 5,500 feet (1,680 meters) above sea level, even higher than Denver.
"When they play there, the ball will behave differently because of air density compared to other stadiums," said Rabi Mehta, an aerospace engineer at NASA Ames Research Center in Moffett Field, Calif. "When watching the games recently, you often see long passes that overshoot, and I think that's because of this effect."
Physics on the field
Drag is the force of air resistance pushing against a ball's motion and slowing it down, while lift is a force causing a ball to swerve off a straight path. Both forces are caused by the presence of air, so with less air molecules around, these forces are reduced. Thus, the same kick in Johannesburg compared with one at sea level would cause a soccer ball to travel faster and on a less curved path.