What was the Mongol postal system? The Mongol postal system was called the Yam and it was extremely fast and reliable. The Mongol Empire was one of the largest empires in history and at its peak it covered 17.8% of the world’s land area. At its greatest extent, it spanned from the edge of Europe […]
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Why did Gilbert and Sullivan fall out? W. S. Gilbert and Arthur Sullivan fell out badly after Gilbert challenged a £500 carpet expense in 1890. The carpet is usually given as the cause of their breakup, but there were many other reasons, and the split had been building for a long time. You may never
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What is metal fatigue? Metal fatigue is where metal becomes weak and can break due to repeated stress. Metals are very strong materials, and we rely on them in our daily lives. Without metals, we couldn’t have a lot of the things that we take for granted, such as tall buildings, bridges, and airplanes. We
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How do plant roots know where water is? Plant roots find water through a process called hydrotropism, which is where they can sense the moisture content of the soil. Not all plants have roots, but the majority do. Mosses and liverworts don’t have roots. They have tiny hairs that they use to hold themselves in
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Why does oil splash when cooking? Oil splashes when cooking because water in the food hits the hot oil and instantly vaporizes into steam. If you have ever dropped food into a frying pan and been sprayed with hot oil, you’lI understand this problem. It basically comes down to the heat of the oil, the
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Why do we get sleepy after eating? We get sleepy after eating because digestion, hormones, and our body clock can all reduce alertness, especially after a large meal. A lot of people notice that after a large lunch it becomes very difficult to stay awake through the afternoon, and the coffee starts to look more
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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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