Why does friction produce heat? Friction produces heat because mechanical energy has to go somewhere, and some of it is converted into the random movement of atoms and molecules, which is heat. Sometimes we need friction to produce heat and sometimes we don’t want it to. If you have ever been out in the cold […]
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Why do house doors open inwards but public doors open outwards? House doors generally open inwards for security and public doors generally open outwards for safety. The majority of front doors open inwards for security. The main purpose of a front door is to keep people and things out of your houses. With a door,
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Why do opposite sides of the brain control opposite sides of the body? Nobody actually knows the real reason why the left side of our brain controls a lot of the functions on the right side of our body, and the right side of the brain controls a lot of the functions on the left
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When did tax start? The earliest evidence of taxation comes from Mesopotamia and Ancient Egypt in roughly 3300 to 3000 BC. This was long before people paid tax in coins, so tax was usually paid in goods or in labor. Some form of taxation probably existed before the earliest evidence we have, but writing was
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Why can you whip cream but not milk? Whipped cream becomes thick because air bubbles are trapped in the cream, creating something called a semi-solid colloid. Milk doesn’t have enough fat to hold the air bubbles in place. You can whip milk into a foam if you whisk it fast enough. This is similar to
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Who was Mrs. Beeton? Mrs. Beeton was Isabella Beeton. If you are British, you have probably heard her name in reference to all of the household management and recipe books that were released in her name. Even if you are not British, there is a strong chance that you have heard of her. I say
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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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