Why does a soccer ball bend without spin?

[Quadruple Bypass]

yes i know the basics of how it curves (bends) in mid air, BUT, why does it bend when there is little to relatively no spin on it? i have noticed this a few times.PS: if you want to catch the craziest bend, here it is... [MEDIA=youtube]-_4WRdLniPY[/MEDIA]&search=roberto%20carlos[/URL]

EDIT: sorry i picked the wrong camera angle link, here is the other camera angle

[PLAIN][MEDIA=youtube]C83X7UBqXAE[/MEDIA]&search=roberto%20carlos[/URL]

 

[Cyrus]

My god that is impressive.

 

[dimensionless]

Are sure it doesn't have spin on it? Often videos can create the illusion that a spinning object is not spinning.

A good wind could also cause the ball to swerve.

 

[rcgldr]

Turbulent air flow. A "knuckleball" in hardball will move around a bit randomly, with little spin on it. I can't see the video though, I'm using IE, and apparently java-script isn't working (although I can see some other videos on you tube).

 

[Quadruple Bypass]

ah no no no, sorry. the video has nothing to do with the question, its just showing what a spinning ball CAN do. sometimes i kick a ball and it has absolutely no spin on it, but it still bends. could it have something to do with the warping of ball? the air inside bouncing from side to side? yea I am really going out on a limb here.

 

[FredGarvin]

Honestly, I can't say for sure.If it truly is not spinning, it would have to be a combination of the unstable flow around the ball coupled with the ridges in the ball's skin. I think you may also have something in the idea of the deformation of the ball too.

The video linked looked like the ball did have spin on it though. However your experience tells you otherwise.

Let me ask you this...can you kick the ball consistantly with no spin? If so, does the ball bend the same way every time?

 

[Quadruple Bypass]

it could have something to do with the ridges and the air flow. and the times i kick it with no spin are the times when i am TRYING to put a spin on it (weird huh?). but its 50/50, so I am not consistant.

 

[FredGarvin]

I'd be interested to see if it broke in the same direction consistantly with no spin. After doing a bit of looking around, I saw some good info on the knucklball pitch. It's path tends to be erratic which makes it hard to hit for the batter and hard to catch for the catcher. That erratic path is definitely due to the stitching on the ball. The same phenomenon must be happening here.