How to Bend the Ball: Reverse Magnus Effect Many soccer players are incredibly picky about what kind of ball they prefer to play with. For example, the official ball of the 2010 World Cup held in South Africa was highly disliked by many players. The Jabulani, the name of the ball used at this specific World Cup, was made unlike any other ball before it. This ball was much smoother than any other ball that the players had ever played with. At first glance, it seems like this wouldn't make much of a difference, but after looking at the physics of it, the smoother a ball is, the less predictable it's flight pattern will be. This is all based upon the reverse Magnus Effect. source: https://twitter.com/jabulaaaani The problem with this specific ball, was that it was so smooth, that it didn't act like a normal soccer ball would while it was in air. When struck with a normal side spin that would cause a normal, rougher, soccer ball to bend in one direction, the Jabulani would bend in unexpected ways. Given a perfectly smooth ball, it can actually bend in the opposite direction! Dr. J.W.M. Bush of MIT says that the cause of this reversing of the Magnus Effect is the roughness of the surface of the ball. Bush comments that when an almost perfectly smooth ball (like a beach ball) and a regular soccer ball are struck, the two have opposite directions of curve. Bush writes: "When the ball is spinning, one expects the drag crisis to be crossed first on the retreating side, where the velocity difference between ball and free stream is minimum. There would thus arise a situation in which the boundary layer is turbulent on the advancing side, and laminar on the retreating side. The resulting delay of boundary layer separation on the advancing side would lead to an asymmetric wake, with air in the wake being deflected in the direction of the retreating side, giving rise to the reverse Magnus effect, and a lift force opposite that expected" (Bush 184). source: http://www.fierceinc.com/blog/fierce-conversations/participate-in-a-beach-ball-conversation source: http://www.globalsources.com/gsol/I/Soccer-ball/p/sm/1049026720.htm#1049026720 A beach ball is so smooth, that it can produce a reversal of the Magnus effect. A normal soccer ball, will only demonstrate the normal Magnus effect.