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In the video below, Derek Muller, of the YouTube channel Veritasium, explains a bizarre behavior of some rotating bodies called the Dzhanibekov Effect. From spinning tennis rackets on Earth to spinning wing nuts in space, and from Soviet era secrets to speculations about the end of the world, Derek’s video is an amazing combination of storytelling, history, and explanation of science principles. Enjoy!
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In fluid dynamics, the field of science that studies the movement of fluids (note that a “fluid” can be also a gas), a vortex is defined as an area of a fluid where the motion of the fluid takes place around an axis, which can be straight or curved. Vortices and their effects range from the quantum realm and the world of microorganisms, to water draining down a toilet, tornadoes, hurricanes, and Earth-sized storms on other planets. Bodies travelling through a fluid generate vortices. These vortices can produce a drag on motion. This vortex drag is reduced in airplanes by appropriate wing design, while migrating birds overcome this drag by flying in a “V” formation. On the other hand, the production of vortices is exploited by insects such as bees to make their flight possible. The study of vortices is important and has generated and will continue to generate many practical applications. In the cool video below, Dianna Cowern (Physics Girl) produces dual vortices in a pool which can be followed by looking at the shadows they project on the bottom. She also uses food coloring to demonstrate that they are connected forming a half circle! Snake charming is an ancient art, but is all trickery. The snake, often a cobra, is not “charmed” or affected in any way by the charmer’s music. The reptile can’t hear the sound of the music. It only sways its body sideways to follow the movement of the tip of the instrument exhibiting a defense reaction against something it perceives as threatening. Additionally, the snake charmers often remove the venom glands of the snakes and sometimes even the fangs to protect themselves. Some go as far as sewing the mouth of the snake shut, which ends up killing the reptile. Shark charming is a different matter. The snout of sharks possesses a set of receptors called Ampullae of Lorenzini. They are named after the Italian physician and ichthyologist, Stefano Lorenzini, who first described them in the 17th century. Sharks use these receptors to detect small electric currents generated by their prey. If you rub the snouts of sharks you can activate these receptors and induce a trancelike state called “tonic immobility”. Scientists working with sharks use tonic immobility to perform several procedures with minimal struggle by the animal. However, some divers perform this for show or for paying customers, which has been criticized. When hydrogen peroxide is combined with soap and a catalyst is added, the hydrogen peroxide decomposes producing heat and releasing oxygen which, due to the soap, generates a large amount of foam (called “elephant toothpaste” by some people). While the generation of a modest amount of elephant toothpaste is often a crowd pleaser at science shows and has even been featured in sitcoms and movies, there are a few rival groups of nerds that are engaged in a cutthroat competition to produce the largest amount of elephant toothpaste ever. The video below chronicles some of the history and the last epic attempt by Nick Uhas and his gang. The end result reminds me a bit of the classic monster movie, The Blob. except that fragments of the stuff even went airborne! There are many things that scientists study that are very interesting and informative, but unfortunately some of them are also quite gross, so who better to talk about these things but, Anna Rothschild, the creator of the aptly named, “Gross Science”. In the video below she talks about the importance of coprolites in archeology. What is a coprolite? Watch the video! |
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