In this article we show why flying and rotating beer mats, CDs, or other flat disks will eventually flip in the air and end up flying with backspin, thus, making them unusable as frisbees. The crucial effect responsible for the flipping is found to be the lift attacking not in the center of mass but slightly offset to the forward edge. This induces a torque leading to a precession towards backspin orientation. An effective theory is developed providing an approximate solution for the disk’s trajectory with a minimal set of parameters. Our theoretical results are confronted with experimental results obtained using a beer mat shooting apparatus and a high speed camera. Very good agreement is found.
The Ig Nobel Prizes honor achievements that make people LAUGH, then THINK.
In the Ig Informal Lectures, some days after the ceremony, the new Ig Nobel Prize winners attempt to explain what they did, and why they did it.
In Podcast Episode #1072, Marc Abrahams presents the 2020 Ig Nobel Prize winner for Medicine Damiaan Denys. He and colleagues Nienke Vulink and Arnoud van Loonreceive won the prize for diagnosing a long-unrecognized medical condition: Misophonia, the distress at hearing other people make chewing sounds.
In the days when it was essential for marine navigators to be able to get a good visual fix on stars and other astronomical objects, many inventors tried to find ways of creating a ‘Marine Chair’ which would stay still while the ship rolled about in the middle of the ocean. Various national governments offered generous prizes for coming up with an invention which worked.
The illustration shows one of the first attempts – which unfortunately didn’t perform as well as was hoped. Le Cosmolabeby Jacques Besson, published in Paris in 1587. As professor Martin J Murphy PhD FAAPM from the Department of Radiation Oncology at Virginia Commonwealth University, US explains :
“Similar devices were proposed later by Galileo, Neville Maskelyne, and others as a means of making astronomical measurements for the determination of longitude at sea. (They didn’t work.) “
For another short history of the not-so-successful development of marine chairs, see this essay from Dr Alexi Baker who was a postdoctoral fellow at CRASSH, University of Cambridge, UK, and is now collections manager at the Division of the History of Science and Technology, Yale Peabody Museum, Connecticut, US.
One picture is perhaps worth 1000 squawks. That picture is figure 3 (captioned “Schematic diagram showing an acid-base imbalance in poultry under heat stress”) in this study:
High environmental temperature alters the poultry health and performances by causing heat stress. Heat stress elicits physiological, behavioral, and production changes in poultry. This review article summarizes these changes along with the strategies that have been used in the poultry industry to ameliorate the adverse effects of heat stress in poultry.
