The physics of human sperm vs. the physics of the sperm whale
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Have you heard of the Great Molasses Flood? In 1919, an industrial accident created a wave of molasses that swept through streets of Boston at 35 miles per hour, killing 21 people in its wake. Over at Scientific American, Ferris Jabr deftly explains why the Reynolds number of molasses made this disaster all the more lethal, and how microbes are faced with an even more sticky situation on a daily basis. (This tragedy also happened recently in Hawaii.)
The low Reynolds number world can be a very counterintuitive place. Here's a neat video that shows the odd behavior of three drops of colored dye in a vat of glycerine. I guarantee you'll be surprised by how it ends.
Because corn syrup is more viscous than water, a swimmer submerged in corn syrup has a low Reynolds number. This has some surprising consequences. This series of videos shows that a corkscrew works better than a paddle in the Low Reynolds number world. This is why sperm and bacteria use corkscrew shaped flagella instead of a paddle.
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