Secret of walking on water uncovered
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A water strider walks on water.
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| MAKING 'ROBOSTRIDER' |
As part of his research, graduate student Brian Chan created "Robostrider," a mechanical water strider.
Made out of a 7-Up can, the mechanical strider has stainless steel wire legs and an elastic band coupled to a pulley to power its middle legs.
The result is a robot that is light enough not to break through the water surface and can travel half a body length per stroke.
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LONDON, England (Reuters) -- So that's how they do it.
If you have ever wondered how insects like water striders walk on water or skim across the surface of ponds, rivers and oceans, scientists in the United States have the answer.
Rather than move by creating waves, as some researchers had thought, the insects use one of their three sets of hairy legs like oars to create vortices or spirals in the water that propel them forward at speeds of up to 150 cm (60 inches) per second.
Professor John Bush of the Massachusetts Institute of Technology and his colleagues who uncovered the secret said that although tiny waves were created, they were not the main driving force.
"The momentum transfer is primarily in the form of subsurface vortices," Bush said in a report in the science journal Nature.
Cams show patterns
Water striders, also known as skimmers, come in hundreds of different species ranging in size from one centimeter (about half an inch) to the giant Vietnamese variety -- 20 times bigger and still able to walk on water.
The researchers uncovered the secret by using sophisticated tracking and a high-speed video camera that showed the curlicue patterns they made.
They also created a mechanical water strider, called Robostrider, based on the real thing.
It is made out of a drinks can, with stainless steel wire legs and an elastic band and pulley as its middle legs.
Copyright 2003
Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
