Physics Equation Developed to Explain Impossible Soccer Kick



At a 1997 soccer match, Roberto Carlos scored a goal against the French national team that seemed physically impossible. The ball seemed to curve around the French players. Physicists couldn't explain the ball's movement:

A group of French scientists, perhaps desperate to prove that at least the laws of physics weren’t actively rooting against their national team, have been able to figure out the trajectory of the ball and, with it, an equation to describe its unusual path.

It all comes down to the fact that, when a sphere spins, its trajectory is a spiral. Usually, gravity and the relatively short distance the ball travels cover up this spiral trajectory, but Carlos was a mere 115 feet away and kicked the ball hard enough to reveal its true spiral-like path. As you can see in the diagram above, the ball would have kept spiraling if gravity (and the netting) hadn’t gotten in the way.


At the link, you can see a video of the kick.

Link | Image: New Journal of Physics

Dumb! They only had to look as far as the local pool hall. It's called putting "English" or "spin" on the ball. A common shot used to get around an opponents ball and into the pocket.
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YES!. People have been curling soccer balls for many years - it's a matter of kicking the ball in the correct manner to make it spin through the air.

I refuse to believe that a spherical object in motion will naturally assume a spiral path - that's nonsense.
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Bend It Like Beckham!

This reminds me of the silly things people were saying about Baseball's curve ball 150 years ago. Most first year physics texts have a detailed explanation.
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Perhaps desperate to prove that at least the laws of physics are not actively rooting against their team, were able to determine the trajectory of the ball, and an equation describing his unusual career.

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Unbelievable, they needed to explain that in 2010! Several sports take advantage of the same principle in so many ways -- in decreasing order of noticeability: table tennis, baseball, tennis, golf, and obviously soccer as well (where the curving is probably more noticeable than in golf).

@Jim M, pool and related games do use the same general principle, but the cause is friction against the table, not against air. Your example is not wrong, but it's counter-intuitive.
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As it has been said, this is lame, as anyone with common sense knows, spinning balls have curve trajectories, in pool, bowling, tennis, table tennis, etc.
Can't deny it is extremely hard to give it that kind of spin, and that shot is noteworthy anyway, but shame on the people talking about physical impossibility or trying to explain what is already obvious. It gives science a bad name, as science doesn't cover these silly topics.
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