The incredible amount of swerve that Subri achieved with his dead ball, struck from the left-hand side of the pitch with his right foot, curving out and back in before dipping past the helpless goalkeeper Mohd Nasril Nourdin in the Pahang goal, seemed to defy physics. A FIFA-backed study has been investigating the aerodynamics behind the swerve of footballs since October , with the research triggered by at-times anomalous ball movement.
Can the experts explain how Subri did it? The wrinkle to the Magnus Effect is how the direction of the curve can reverse. In the article, Professor Bush discusses how a completely smooth ball may change the curve direction. He explains this as a result of the ball surface creating a boundary layer. This essentially means the ball will curve in the expected direction. Its because soccer balls have never been completely smooth until only the last few years.
It will be interesting to see if technology continues to emerge, and soccer balls evolve to eventually curve in the expected direction. If new, smooth soccer balls are manufactured and sold, would it change the way soccer is played in some parts of the world?
Would poorer places around the world still have to play with older soccer balls and therefore an older version of the game? What are the general peculiarities of To Score its First Penalty betting? How can I benefit from placing How to deal professionally with To Score in the First Half? What are the general peculiarities of To Score What does Over mean in betting? How to understand if an Over bet is profitable? Over means a wager on the When are the races in Coventry held? What does Coventry mean in races?
Coventry is one of the most popular tracks for What does neutral site mean? How is neutral site translated from English in betting shops? Who has the advantage of What does the term show mean in the US? What do players mean when they say show in horse races? When this happens we say that the boundary layer is "tripped" and since most of footballs' actions such as kicking or throwing take place above the critical speed the ball can be moved around in a pacey manner.
When the ball rotates - see graphic 3 - the boundary layer remains tripped but the air flow separation around the ball is distorted. Separation occurs earlier on the side rotating against the flow and later on the side rotating in the same sense as the flow. This causes a pressure differential and a deflecting force which is responsible for moving the ball in the air in a free kick.
A baseball has only two panels It was not realised for many years that the boundary layer was tripped by surface "imperfections", in fact by the slight indentations where the ball's panels are joined together. More panels means more seams and greater aerodynamic stability but panel designs have varied enormously over the years.
For example, the familiar hexagon-pattern ball has 32, the classic English model The new World Cup ball, Adidas' Teamgeist, has only fourteen panels, however. Might this be the factor behind the disquiet expressed by Jens Lehmann? To see why this might be so we can take a look at a very simple object, the baseball which has only two panels separated by a continuous seam.
This "curveball" is very similar to a swerving free kick and the rotating seam trips the boundary layer in much the same way as a football does. Occasionally though, pitchers serve up a wicked delivery known as the "knuckleball".
This bobs about randomly in flight and is very disconcerting for batters. It happens because pitchers throw the ball with very little spin. Then, as the limited seam rotates lazily in the air flow, it trips the boundary layer at certain points on the surface. This causes an unpredictable deflection which may be completely reversed when another portion of the seam rotates into the critical position.
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