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There is an amazing object called “Prince Rupert drop”. It is so called because a German nobleman, Prince Rupert, brought some of these tear shaped objects (they are also known as Bavarian Tears) to the King of England in 1660, who in turned them over his scientists for analysis. What is exceptional about the Prince Rupert drops is that it combines great resistance to forces applied to the head of the drop along with a great fragility in the tail section of the drop where a small tear can produce an explosive disintegration of the whole drop. This derives from the way the drop is made. The Prince Rupert drop is basically a gob of molten glass that is dropped in water. The glass molecules on the surface of the drop cool rapidly creating a hard layer. This exterior hard layer is pulled in by the slowly cooling deeper layers in the center of the drop pushing the molecules in the exterior layer against each other. This gives rise to an interplay of compression forces in the outer layer along with tensile forces in the inner layers that is responsible for both the great strength and fragility of the Prince Rupert drop. Destin from SmarterEveryDay gives an excellent visual explanation of this process in the video below where he also uses high-speed cameras to visualize the explosion of Prince Rupert drops. You can also check Destin’s other video where he fires bullets at Prince Rupert drops!
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When most people think about erosion, they think about water, but wind can also be a significant erosive force. In most places wind acts in concert with water to produce erosion, but in many desert environments, wind is often the predominant erosive force sculpting rocks into amazing shapes. The erosion caused by wind is called “eolic erosion”.  Remarkable Rocks, Kangaroo Island, Australia  Ayers Rock (Uluru), Australia  Top Left: California Coast; Right: Alabama Hills, California; Bottom Left, Badlands National Park, North Dakota Since ancient times human beings have recognized the power of wind, and they have learned to harness it constructing mills and water pumps driven by air currents. In present times we are using wind turbines to produce clean energy.  Wind Turbines, West Virginia However, one of the least recognized uses of wind is in art. I have previously mentioned the use of vertical turbines in the sport of Wind Dancing. We are all also aware of wind chimes, but have you ever heard of whirligigs? See the video below. These kinetic sculptures were made by artist Vollis Simpson. They are in the Vollis Simpson Whirligig Park in Wilson, North Carolina. The structures convert the kinetic energy supplied by the wind into mechanical energy used to produce movement in the sculptures. All the photographs are by the author and can only be used with permission. The video below shows a Foucault pendulum at the Science Museum of Virginia in Richmond. This device was conceived originally by French physicist Jean Bernard Léon Foucault in 1851 to demonstrate the rotation of the Earth. While the plane of oscillation of the pendulum remains constant, it nevertheless experiences an apparent deflection in its movement visualized here by the knocking down of the pegs on the ground. This deflection, which occurs clockwise in the Northern hemisphere and counterclockwise in the Southern hemisphere, is due to the rotation of the Earth under the pendulum. The deflection of the pendulum can also be used to calculate latitude. Human beings cannot perceive light in the infrared wavelengths unlike some snakes. However, we can build devices such as cameras that detect light in the infrared and then color code the images so we can see them. I found one such camera at the NASA Goddard Space Flight Center in Greenbelt, Maryland. In the video below, white and red are the warmest while purple and blue are the coldest. Notice how my mustache and glasses are cooler than the surrounding areas. |
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