Feeds

Boffins explain greatest ever free kick

Roberto Carlos and his amazing exponential spiral

Protecting against web application threats using SSL

Scientists have agreeably concluded that Roberto Carlos's 1997 free kick against France - a seemingly impossible blast into the back of the net from 115ft - was not the fluke some have claimed.

While hapless French keeper Fabien Barthez might have taken solace from the thought that perhaps a gust of wind had accounted for the ball's improbable trajectory, the fact is that it was all down to Carlos and his amazing exponential spiral.

That's according to a team of researchers from the École Polytechnique in Palaiseau, near Paris, who demonstrated that while the ball's trajectory initially conformed to the Magnus effect, which gives a spinning sphere a curved path, the distance of this particular free kick added a surprise ending.

By firing plastic balls into a tank of water, the boffins showed that if a football's spin speed remains constant, "its trajectory follows an exponential spiral", with the bend "surprisingly" increasing as drag slows the ball down.

In the final phase, where both velocity and spin decrease, the ball tends to follow a straight line before hitting the back of the net.

The distance here is critical. Researchers Christophe Clanet and David Quéré explained: "When shot from a large enough distance, and with enough power to keep an appreciable velocity as approaching the goal, the ball can have an unexpected trajectory.

"Carlos' kick started with a classical circular trajectory but suddenly bent in a spectacular way and came back to the goal, although it looked out of the target a small moment earlier.

"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."

The full explanation of the Roberto Carlos exponential spiral can be found here in the latest edition of New Journal of Physics. ®

Reducing the cost and complexity of web vulnerability management

More from The Register

next story
PORTAL TO ELSEWHERE scried in small galaxy far, far away
Supermassive black hole dominates titchy star formation
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Edge Research Lab to tackle chilly LOHAN's final test flight
Our US allies to probe potential Vulture 2 servo freeze
Europe prepares to INVADE comet: Rosetta landing site chosen
No word yet on whether backup site is labelled 'K'
Cracked it - Vulture 2 power podule fires servos for 4 HOURS
Pixhawk avionics juice issue sorted, onwards to Spaceport America
Archaeologists and robots on hunt for more Antikythera pieces
How much of the world's oldest computer can they find?
Who wants to be there as history is made at the launch of our LOHAN space project?
Two places available in the chase plane above the desert
prev story

Whitepapers

Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.