Sunday, February 12, 2006

Too Much Time on Their Hands Department

It's a question that has taxed generations of the finest minds in physics: do humans swim slower in syrup than in water? And since you ask, the answer's no. Scientists have filled a swimming pool with a syrupy mixture and proved it.

"What appealed was the bizarreness of the idea," says Edward Cussler of the University of Minnesota, Minneapolis, who led the experiment. It's a question that also fascinated his student Brian Gettelfinger, a competitive swimmer.

Cussler and Gettelfinger took more than 300 kilograms of guar gum, an edible thickening agent found in salad dressings, ice cream and shampoo, and dumped it into a 25-metre swimming pool, creating a gloopy liquid twice as thick as water. "It looked like snot," says Cussler.

The reason you don't swim slower in syrup, explains Cussler, is that while you experience more "viscous drag" (basically friction from your movement through the fluid) as the water gets thicker, you generate more forwards force from every stroke. The two effects cancel each other out.

Cussler and his team are looking forward to repeating the experiment with a swimming pool filled with snot.

The perfect swimmer, whether in water or syrup, has powerful muscles but a narrow frontal profile. "The best swimmer should have the body of a snake and the arms of a gorilla," recommends Cussler.

Genetic modification experiments begin next month.

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