How does a suction cup work? A suction cup works by creating a partial vacuum and using air pressure to keep the cup stuck to a wall. A suction cup stays on a wall because of the weight of the air. Suction cups are made of rubber, silicone, or plastic that is flexible enough to […]
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Why is there a market day? There is a market day because it used to be difficult to get food and goods to a market, so it made sense to have one day when suppliers and buyers would all come together. Thanks to supermarkets, refrigeration, and globalized distribution networks, it is easy to forget how
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Why do we get a falling feeling in our stomachs when we drop on a roller coaster? The falling feeling we get in our stomachs on a roller coaster happens because some of the organs in our abdomen, especially the stomach and intestines, are more free to shift than organs that are more firmly supported.
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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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How did people wake up before alarm clocks? Before alarm clocks, people woke up naturally or were woken by outside noises. In cities, they might have used candle clocks, been woken by church bells, or paid a professional knocker-upper. The idea of needing to be awakened by an alarm clock is a relatively recent problem.
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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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Why did it take so long for papermaking to reach Europe? It took so long for papermaking to reach Europe because they had materials that they thought were superior, they were resistant to Islamic influence, not many people could read or write, and the world was not as small then as it is now. Writing
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Why don’t figure skaters get dizzy when they spin? Figure skaters do get dizzy when they spin, but they learn to manage it because they have trained their brains and vestibular systems to cope with the sensation. The sensation of dizziness comes about because of the way our balance system works. There are three parts
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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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How can kangaroos hop so fast? Kangaroos can hop so fast because they have very large tendons in their legs that act like natural springs. Kangaroos are native to Australia and there are four species. Those are the red kangaroo, antilopine kangaroo, eastern grey kangaroo, and western grey kangaroo. The largest and the fastest species
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