Some animals have the ability to shake water off themselves very quickly. Physicist and engineers covet this ability, and want to imitate it. In order to do so, they've filmed some amazing footage of different animals shaking themselves dry, always in slow motion, and sometimes in x-ray.
Via Georgia Tech.
The dogs have a fluorescent marker clipped to them, to let scientists measure how far their skin moves. They're taken for a walk under a water trap that releases a shower on top of them. They then shake themselves off while the camera takes in the details, including the hilariously floppy jowls.
Dogs are able to clear about seventy percent of the water off their fur in only a few seconds. Scientists believe this is because they have a good overall rotation, as well as very loose skin. This maximizes the way the fur moves and lets them try off quick.
Smaller animals have quicker shakes. Small dogs shake faster than large ones, cats shake faster than that, and this rat is going fast even in ultra-slow motion. Scientists measured the shaking force in gravities, and found that 10 gravities was the least amount of force exuded by any shaking animal.
Scientists tried the video with goats, pigs, sheep, and mice, all of which shook efficiently. Only the kangaroo was a dud, giving an irritable shake of its head and nothing more. The researchers believe that the large hindquarters of the kangaroo inhibited shaking, and the dry climate where it evolved might have be so short on water that no instinct to shake off was necessary.
Fortunately, scientists did not only rely on animals. They attached a camera to a "wet dog simulator" and spun it around to watch drops seemingly leap off the end of a small pole. This would be even cooler if the lights behind it were gone. It's hoped that studying the shaking technique and speed of animals might help engineers build equipment that can shake water or sand off itself, rather than requiring it to be wiped away.
If you want to see more videos, check out the page at Georgia Tech.