Saturday, July 10, 2010

The Physics of Smooth Balls

One could go in so many different directions with a title like that, but I'll play dumb right right now. :)

There have been many reports on the physics of soccer with the World Cup about to reach its climax (!) today (read this and this). So why not another one? This report discusses the differences between a smooth soccer ball versus one that is not.

“You might think if you make a ball very, very smooth, it will fly through the air better than a ball that is rough,” says John Eric Goff, chair of the physics department at Lynchburg College and author of Gold Medal Physics: The Science of Sports.

You might think that, but you’d be wrong.

“As the air goes around a sphere, or one of these sports balls, it forms a little layer near the surface of the sphere called the boundary layer,” says Goff. A rough surface makes that boundary layer break down at lower speeds.

“And what that means is the drag force on the ball, the air resistance, goes down slightly,” he says.

Now you know why a soccer ball has those "panels". Now, the issues with the Jabulani balls are a completely different matter.


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