Saturday 23 October 2010

Wet dog physics

I am indebted to Entangled States for this link to an article on the physics of how a wet dog shakes itself dry. It shows how surface tension and the size of the animal combine to determine that shake frequencies decline to 4Hz for an ideal, infinitely large labrador. If there is, indeed, anything ideal about an infinitely large labrador. I reckon it would break the furniture.

When we read this, we see how something ontologically simple - a furry animal drying itself - becomes remarkably complex as we look at the interplay of the component elements - surface tension, a relationship based on a fractional power of the radius. And yet each of these components is itself terribly simple when broken down to Van Der Waals attractions etc.  I wonder myself whether the difference between the r0.5 relationship predicted by the researchers and the observed r0.75 might be down to electrostatic as well as surface tension forces. Drayton, of course, reckons the difference between the two formulae is down to some kind of supernatural intervention. But I reckon that's just the old "dog of the gaps" argument.

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