The Physics Of Roberto Carlos

As evidenced by the aerodynamic qualities of his glistening dome and breaking land-speed records with every third free kick, Roberto Carlos is a very, very scientific man.

He’s also inspired scientists, particularly that free kick back in 97 – you don’t need to hit play to know the one I’m referring to – to determine whether he “defied physics” or if he’s not of this world.

They’ve ultimately determined it’s neither, while I think it’s a little bit of both – Barthez just got Roberto Carlos’d.

Your physics lesson for the day.

Dr Clanet described this path as a “snail-shell shaped trajectory”, with the curvature increasing as the ball travels.

Because Roberto Carlos was 35m (115ft) from the goal when he kicked the ball, more of this spiral trajectory was visible. So the apparently physics-defying sharp turn of the ball was actually following a naturally tightening curve.

Dr Clanet and his colleague David Quere were studying the trajectory of bullets when they made their sporting discovery.

They used water and plastic balls with the same density as water to “simplify the problem”.

This approach eliminated the effects of air turbulence and of gravity and revealed the pure physical path of a spinning sphere.

“On a real soccer pitch, we will see something close to this ideal spiral, but gravity will modify it,” explained Dr Clanet.

“But if you shoot strongly enough, like Carlos did, you can minimise the effect of gravity.”

The crucial aspect of the wonder strike, according to the scientists, was the distance the ball had to travel to beat Fabian Barthez.

“If this distance is small,” said Dr Clanet, “you only see the first part of the curve.

“But if that distance is large – like with Carlos’s kick – you see the curve increase. So you see the whole of the trajectory.”

And thus concludes the first time we’ve ever informed you of something useful.

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Category: World Football