Why do plugs spark when you pull them out? Plugs spark when you pull them out because, for a very brief moment, the electrical current can continue across the tiny gap as the plug loses contact with the socket. It does not continue for long, but it can continue just long enough to ionize the […]
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What is the rarest coin in the world? There are several possible candidates for the rarest coin in the world, but the most widely recognized contender is the 1933 Saint-Gaudens Double Eagle. This is a difficult question because there have been so many different coins over the thousands of years since coins were first used
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How do cranes balance? Cranes balance by using a system of counterweights, a stable base, and computers that monitor the load and angle of the crane at all times. The idea behind counterweights is fairly simple to understand, and it can be tested on a desk with a ruler, a pencil, and some heavy objects.
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What is the Janney coupler? The Janney coupler is a device that goes between train cars to join them together. It was a revolutionary jump in railroad technology and is still used today, over 150 years later. If you have ever ridden on a train and you have looked at the coupling that hold the
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How does a ship’s anchor work? A ship’s anchor works because the anchor digs into the seabed and the heavy chain creates a huge amount of resistance while keeping the pull on the anchor low and steady. Most people think that when ships rest at anchor, the only thing holding them in place is the
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Do we still need weather balloons? Yes, weather balloons are still needed. Satellites can provide a lot of data, but they still cannot sample the atmosphere directly from inside it, and they are far more expensive. There are thousands of satellites in orbit around Earth at the moment, so it is easy to assume there
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Why do we use feet and inches, and why do eggs come in dozens? Why do we use feet and inches, and why do eggs come in dozens? We basically use feet as measurements because everybody has feet, and eggs come in dozens because it is easier to divide them up. Imperial measurements are slowly
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Why do printers use CMYK not RGB? Printers use CMYK because paper reflects light rather than emitting it. CMYK stands for Cyan, Magenta, Yellow, and Black. Black has the letter K because it stands for “key plate.” In old-style printing, the key plate was the plate that carried the most detail and definition. Because most
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Why do power stations have giant chimneys? The large conical towers that power stations usually have are giant cooling stacks, which are there to remove excess heat after the electricity generation process. When we see them in the distance, white clouds are belching out of them, but this is mostly water vapor that becomes visible
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Do submarines still use periscopes? Yes, submarines do still use periscopes, although they now combine them with many other high-tech sensors as well. At its simplest, a periscope uses two angled reflectors to send light down a long tube. A basic periscope looks a bit like a straightened “S.” The top opening faces whatever is
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