A cat's tongue scarcely brushes the surface - not scooping up liquid like a dog, but pulling it up from above, in a manner that seems to defy gravity.
More explanation later, but briefly: With each darting flick of the tongue, the animal relies on the property of adhesion and Bernoulli's principle - the same phenomenon involved in making baseballs curve and airplanes fly. Lions and other larger cats do it, too, though their larger tongues lead them to do it fewer times per second, at a speed the researchers were able to predict with a mathematical formula.
The study's authors, who hail from the Massachusetts Institute of Technology, Virginia Tech, and Princeton University, pursued the topic without funding, largely out of intellectual curiosity. Yet in their paper, they wrote that the findings could lead to research in soft robotics - a growing field that derives inspiration from other flexible structures in the animal kingdom, such as elephant trunks and octopus arms.
Still, they are prepared for bemused reactions from those who may not immediately perceive the beauty in commonplace things.
Just ask Princeton's Jeffrey M. Aristoff, one of the authors. At a physics conference later this month, he will be presenting research on another everyday phenomenon, the aerodynamics of jumping rope.
Frame by frame
"It's something you see every day," Aristoff said of things such as the cat's tongue or the jump rope, "but you never really think to ask: 'How does it work? What is it useful for?' "
The cat study began when Roman Stocker, Cutta Cutta's owner and an associate professor of civil and environmental engineering at MIT, puzzled over how the feline was getting milk or water into his mouth. The tongue moved too fast for Stocker to see clearly, so he enlisted colleagues to help him capture it on film, then advanced the pictures frame by frame.
