Ball-Physics World Cup Style

Every World Cup Adidas produces a new ball for the tournament and with it a firestorm of punditry and speculation. Wired magazine goes a long way to towards stating the obvious about the current TeamGeist ball (and it’s flight patterns) in this tournament. In fact it was so obvious that even yours-truly, a physics-phobic, was able to explain it months ago.

Adidas have produced the roundest ball ever mass-produced. This makes the ball ultra predictable when rolled along the felt-smooth World Cup surfaces. But in the air a smoother skin means less spin and less spin makes the ball more prone to sudden changes in direction as the ball accelerates and then decelerates..

The same principle is familiar to golfers, who rely on backspin to keep shots straight. Part of why today’s drivers fly striaghter has to do with optimising the backspin (this is also why most golfers hit hybrid clubs straighter than their matching long irons). It is also why shots hit from certain kinds of lies (like deep rough) often fly erratically when compared to the same shot hit from a fairway.

We may well see some spectacular long-range goals with this TeamGeist ball (and quite a few teams have been trying to create lots of occasions for such shots) and we might even see something spectacular from a set piece (like Riquelme’s near goal from a corner last night, or Totti’s spectacular free kick drive in Italy’s opening game). However, we are unlikley to see many goals from short range freekicks. We will also continue to see goalkeepers opting to lauch the ball either low and hard, or high into the clouds.

[tags] Teamgeist, World Cup [/tags]