Carlos ’97 free kick no fluke, say French physicists

While their research quickly confirmed the long-known Magnus effect, which gives a spinning ball a curved trajectory, their research revealed fresh insight for spinning balls that are shot over a distance equivalent to Roberto Carlos’ free kick.

The friction exerted on a ball by its surrounding atmosphere slows it down enough for the spin to take on a greater role in directing the ball’s trajectory, thereby allowing the last moment change in direction, which in the case of Carlos’ kick left Barthez defenceless.
The researchers refer to their discovery as the ‘spinning ball spiral,’ comparing the spiralling effects of Roberto Carlos’s kick with the shorter-distance (20-25 m) ‘circular’ free kicks shot by the likes of Beckham and Platini.

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‘People often noticed that Carlos’ free kick had been shot from a remarkably long distance; we show in our paper that this is not a coincidence, but a necessary condition for generating a spiral trajectory.’

Here’s the kick in question: