Researchers created a staircase-like piece of brass and make water droplets climb up the stairs.If a pan's really hot, the water starts to evaporate before it even touches the surface. The evaporating water, in the airy form of a water-vapor cushion, holds the droplet above the pan. With moves as smooth as Fred Astaire, the droplet glides around on air.
When scientists heated a piece of brass with sawtooth ridges — a thing that looks like a ratchet — water drops traveled quickly, and in one direction: up.
"The drop rides along on the vapor like a boat on a river," said physicist Heiner Linke from the University of Oregon. "The vapor is generated between the droplet and the ratchet's surface in a narrow gap, about the width of a human hair. The vapor needs a way to get out of there, and it's going to take the easiest way out. There's always going to be one direction in which it's easier to get out."
The escaping vapor pulls the droplet along in the same direction.
Link & Image: MSNBC
Tags: Water | Vapor | Stairs
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