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Clint Dempsey scored Team USA's first goal during the FIFA World Cup 2014 Group G preliminary match against Ghana. |
FIFA World cup qualification: is it a fair game?
FIFA has 208 member football associations from around the world all clamoring to qualify for each World Cup tournament and reap the massive $8 million appearance fee as well as further windfalls and lucrative merchandising revenues. With fierce competition for qualification, is FIFA allocating the 32 places fairly or are processes biased by finances and politics? New research, published in the journal Soccer & Society, suggests that a more transparent allocation processes is urgently required. Without this, experts at Canada's Sprott School of Business argue, FIFA will be open to the accusation it is more concerned with financial gain from the World Cup than showcasing the very best football.
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The World Cup generates 90% of FIFA revenues. Stone and Rod believe that this economic success should be used by FIFA, in the cause of corporate social responsibility, to expand participation. Without that, the question is asked "has world football become the means to an end in terms of money as the ultimate objective?"
- Story Source: Materials provided by Taylor & Francis. Christian Stone, Michel Rod. Unfair play in World Cup qualification? An analysis of the 1998–2010 FIFA World Cup performances and the bias in the allocation of tournament berths. Soccer & Society, 2014
New ball to showcase talent in World Cup
Physics experts believe the new soccer ball created for the 2014 FIFA World Cup is a “keepers’ ball”. The new ball, called Brazuca, should be much more predictable than the 2010 World Cup ball, Jabulani, which was less-than-affectionately labelled a 'beach ball' because of its sometimes erratic flight path.
"The Brazuca has very deep grooves -- it's much rougher than Jabulani -- and this creates a different pattern of air flow around the ball," says Professor Derek Leinweber, Professor of Physics in the University's School of Chemistry and Physics. He has previously written about and lectured on the aerodynamics of cricket balls, golf balls and earlier World Cup soccer balls.
"The Jabulani was much smoother than the Brazuca with smaller grooves and ridges across its surface," says Professor Leinweber. "That meant the ball had to be moving much faster before the airflow around the ball changed from smooth to turbulent. As this shift to turbulent airflow occurred at high speeds, the ball could make some pretty erratic movements on the way to the net.
"In contrast the Brazuca, with its deeper grooves, hits that turbulent air flow at a lower speed with the result that the ball is much more predictable. In many ways, it's a return to the aerodynamics of the old 32-panel ball."
Mr Kiratidis says he believes players taking hard and fast shots in this World Cup won't find the Brazuca as easy to bend into the net as they did with the Jabulani.
- Story Source: Materials provided by University of Adelaide. "New ball to showcase talent in World Cup." ScienceDaily.
How does a soccer ball swerve?
It happens every four years: The World Cup begins and some of the world's most skilled players carefully line up free kicks, take aim -- and shoot way over the goal.
The players are all trying to bend the ball into a top corner of the goal, often over a wall of defensive players and away from the reach of a lunging goalkeeper. Yet when such shots go awry in the World Cup, a blame game usually sets in. Players, fans, and pundits all suggest that the new official tournament ball, introduced every four years, is the cause.
Many of the people saying that may be seeking excuses. And yet scholars do think that subtle variations among soccer balls affect how they fly. Specifically, researchers increasingly believe that one variable really does differentiate soccer balls: their surfaces. It is harder to control a smoother ball, such as the much-discussed "Jabulani" used at the 2010 World Cup. The new ball used at this year's tournament in Brazil, the "Brazuca," has seams that are over 50 percent longer, one factor that makes the ball less smooth and apparently more predictable in flight.
"The details of the flow of air around the ball are complicated, and in particular they depend on how rough the ball is," says John Bush, a professor of applied mathematics at MIT and the author of a recently published article about the aerodynamics of soccer balls. "If the ball is perfectly smooth, it bends the wrong way."
By the "wrong way," Bush means that two otherwise similar balls struck precisely the same way, by the same player, can actually curve in opposite directions, depending on the surface of those balls. Sound surprising?
How a ball curves: The Magnus Effect
It may, because the question of how a spinning ball curves in flight would seem to have a textbook answer: the Magnus Effect. This phenomenon was first described by Isaac Newton, who noticed that in tennis, topspin causes a ball to dip, while backspin flattens out its trajectory. A curveball in baseball is another example from sports: A pitcher throws the ball with especially tight topspin, or sidespin rotation, and the ball curves in the direction of the spin.
In soccer, the same thing usually occurs with free kicks, corner kicks, crosses from the wings, and other kinds of passes or shots: The player kicking the ball applies spin during contact, creating rotation that makes the ball curve. For a right-footed player, the "natural" technique is to brush toward the outside of the ball, creating a shot or pass with a right-to-left hook; a left-footed player's "natural" shot will curl left-to-right.
So far, so intuitive: Soccer fans can probably conjure the image of stars like Lionel Messi, Andrea Pirlo, or Marta, a superstar of women's soccer, doing this. But this kind of shot -- the Brazilians call it the "chute de curva" -- depends on a ball with some surface roughness. Without that, this classic piece of the soccer player's arsenal goes away, as Bush points out in his article, "The Aerodynamics of the Beautiful Game," from the volume "Sports Physics," published by Les Editions de L'Ecole Polytechnique in France.
"The fact is that the Magnus Effect can change sign," Bush says. "People don't generally appreciate that fact." Given an absolutely smooth ball, the direction of the curve may reverse: The same kicking motion will not produce a shot or pass curving in a right-to-left direction, but in a left-to-right direction.
Why is this? Bush says it is due to the way the surface of the ball creates motion at the "boundary layer" between the spinning ball and the air. The rougher the ball, the easier it is to create the textbook version of the Magnus Effect, with a "positive" sign: The ball curves in the expected direction.
"The boundary layer can be laminar, which is smoothly flowing, or turbulent, in which case you have eddies," Bush says. "The boundary layer is changing from laminar to turbulent at different spots according to how quickly the ball is spinning. Where that transition arises is influenced by the surface roughness, the stitching of the ball. If you change the patterning of the panels, the transition points move, and the pressure distribution changes." The Magnus Effect can then have a "negative" sign.
From Brazil: The "dove without wings"
If the reversing of the Magnus Effect has largely eluded detection, of course, that is because soccer balls are not absolutely smooth -- but they have been moving in that direction over the decades. While other sports, such as baseball and cricket, have strict rules about the stitching on the ball, soccer does not, and advances in technology have largely given balls sleeker, smoother designs -- until the introduction of the Brazuca, at least.
There is actually a bit more to the story, however, since sometimes players will strike balls so as to give them very little spin -- the equivalent of a knuckleball in baseball. In this case, the ball flutters unpredictably from side to side. Brazilians have a name for this: the "pombo sem asa," or "dove without wings."
In this case, Bush says, "The peculiar motion of a fluttering free kick arises because the points of boundary-layer transition are different on opposite sides of the ball." Because the ball has no initial spin, the motion of the surrounding air has more of an effect on the ball's flight: "A ball that's knuckling … is moving in response to the pressure distribution, which is constantly changing." Indeed, a free kick Pirlo took in Italy's match against England on Saturday, which fooled the goalkeeper but hit the crossbar, demonstrated this kind of action.
Bush's own interest in the subject arises from being a lifelong soccer player and fan -- the kind who, sitting in his office, will summon up clips of the best free-kick takers he's seen. These include Juninho Pernambucano, a Brazilian midfielder who played at the 2006 World Cup, and Sinisa Mihajlovic, a Serbian defender of the 1990s.
And Bush happily plays a clip of Brazilian fullback Roberto Carlos' famous free kick from a 1997 match against France, where the player used the outside of his left foot -- but deployed the "positive" Magnus Effect -- to score on an outrageously bending free kick.
"That was by far the best free kick ever taken," Bush says. Putting on his professor's hat for a moment, he adds: "I think it's important to encourage people to try to understand everything. Even in the most commonplace things, there is subtle and interesting physics."
YouTube Video: Bending it like Beckham
- Story Source: Materials provided by Massachusetts Institute of Technology, original article was written by Peter Dizikes. J.W.M. Bush. The Aerodynamics of the beautiful game. Sports Physics, 2013
Soccer-related facial fractures examined
Fractures of the nose and other facial bones are a relatively common and potentially serious injury in soccer players, reports a Brazilian study. Through their analysis, researchers report that he nose and upper jaw (maxilla) accounted for 35 percent of fractures and the cheekbone (zygomatic bone) for another 35 percent. Most of the remaining fractures were of the lower jaw (mandible) and eye socket (orbit). Eighty-seven percent of the injuries were caused by collision with another player; the rest occurred when the player was struck by the ball.
- Story Source: Materials provided by Wolters Kluwer Health: Lippincott Williams and Wilkins. Dov C. Goldenberg, Gal M. Dini, Max D. Pereira, Augusto Gurgel, Endrigo O. Bastos, Purushottam Nagarkar, Rolf Gemperli, Lydia M. Ferreira. Soccer-related Facial Trauma. Plastic & Reconstructive Surgery Global Open, 2014
Why reaching the top in soccer is all in the mind, not the feet
The mental edge that drives Premier League soccer players to succeed from a young age, including dealing with criticism, confronting challenges after repeated failures, and not being intimidated by others, has been outlined by researchers. "The report found that mentally tough players demonstrated a commitment to learning, had a strong level of trust with their coach, were more compliant with instructions and were always seeking ways to improve," researchers say.
- Story Source: Materials provided by University of Lincoln. Clive Cook, Lee Crust, Martin Littlewood, Mark Nesti, Jacquelyn Allen-Collinson. ‘What it takes’: perceptions of mental toughness and its development in an English Premier League Soccer Academy. Qualitative Research in Sport, Exercise and Health, 2014
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