The Biomechanics of Poo and Pee

Abstract

Eat, defecate, repeat. Nearly all animals must excrete their waste in solid and liquid form, yet the underlying physics of this process is poorly understood. In this talk, I present experiments and theory for efficient waste ejection by mammals. Over the last several years, we have filmed the private bathroom processes of over 87 species of mammals at the Atlanta Zoo. Although urine and feces volume can vary over 100-fold between an elephant and a dog, their urination and defecation times are relatively constant, around 21 and 12 seconds, respectively. This talk has been banned in certain locations.

Biography

Dr. David Hu is a mechanical engineer who studies the interactions of animals with water. His team has discovered how dogs shake dry, how insects walk on water, and how eyelashes protect the eyes from drying. Originally from Rockville, Maryland, USA, he earned degrees in mathematics and mechanical engineering from M.I.T., and is now Associate Professor of Mechanical Engineering and Biology and Adjunct Professor of Physics at Georgia Tech. He is a recipient of the National Science Foundation CAREER award for young scientists, the Ig Nobel Prize in Physics, and the Pineapple Science Prize (the Ig Nobel of China). He serves on the editorial board of Nature Scientific Reports and The Journal of Experimental Biology. His work has been featured in The Economist, The New York Times, Saturday Night Live, and Highlights for Children. He has defended basic research in a Scientific American article, Confessions of a Wasteful Scientist. He lives with his wife Jia and children Harry and Heidi in Atlanta, Georgia.

All students and staff welcome.

Tea and cakes available in the Magnet Café foyer, James Clerk Maxwell Building, KB from 16.30.