Scientific and Educational Reports of the Faculty
of Science and Technology, Kochi University
Vol. 3 (2020), No. 3

Projectile Trajectory of Penguin's Faeces and Rectal Pressure Revisited

Hiroyuki Tajima1 and Fumiya Fujisawa2

1Department of Mathematics and Physics, Kochi University, Kochi 780-8520, Japan
2Katsurahama Aquarium, Kochi 781-0262, Japan


We discuss a trajectory of penguins' faeces after the powerful shooting due to their strong rectal pressure. Practically, it is important to see how far faeceses reach when penguins expel them from higher places. Such information is useful for keepers to avoid the direct hitting of faeceses. We estimate the upper bound for the maximum ight distance by solving the Newton's equation of motion. Our results indicate that the safety zone should be 1.34 meters away from a penguin trying to poop in typical environments. In the presence of the viscous resistance, the grounding time and the ying distance of faeces can be expressed in terms of Lambert W function. Furthermore, we address the penguin's rectal pressure within the hydrodynamical approximation combining Bernoulli's theoremand Hagen-Poiseuille equation for viscosity corrections. We found that the calculated rectal pressure is larger than the estimation in the previous work.



Received: June 29, 2020
Reviewed by anonymous referee(s), and accepted: July 2, 2020
Published: July 14, 2020

発行者:高知大学理工学部 〒780-8520 高知県高知市曙町二丁目5-1
Faculty of Science and Technology, Kochi University, Kochi, 780-8520 Japan
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