How did people make the first scales accurate? They made them accurate by using simple physics, careful craftsmanship, and agreed standard weights. Weighing scales are incredibly simple when they are looked at from the outside. At their simplest, there are two dishes hanging from either end of a bar. In the center of the bar […]
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Is an embassy really foreign soil? No. An embassy is not foreign soil. It is still inside the country where it is located, but it is protected by special rules and immunities. The idea that countries own the land their embassy is on and that it becomes foreign soil is very common, but it is
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Why does jaundice turn people yellow? Jaundice turns people yellow because a yellow-orange pigment called bilirubin builds up in the blood and body tissues. The word jaundice came into English from French. In Old French, jaune meant yellow, and that came from a Latin word meaning greenish-yellow. That is why jaundice has always been connected
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Why is it called Area 51? The simple answer is that it was a map designation, but the exact reason why that number was chosen is not completely clear. The site at Groom Lake was near the Atomic Energy Commission’s Nevada Proving Ground, where nuclear testing was carried out. The land there was divided into
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What was the first arms race? To be honest, nobody knows, and this is probably not something we can ever know. Arms races are probably older than written history. Most likely, human civilization has been a trail of one arms race after another. An arms race happens when two or more groups compete to make
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How do squirrels find where they buried their nuts? Squirrels find their buried nuts by using spatial memory, visual landmarks, and their sense of smell. They also bury far more nuts than they need, which is useful because they will not find every single one again. We imagine squirrels only eating acorns, but they actually
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Why does pumice float? Pumice floats because it has a very low density. This is because of all the gas-filled holes inside it. Whether or not something floats depends on how much water it can displace. Objects float in water if they are positively buoyant, which means they can displace more water than their own
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How does ivy grip walls? Ivy grips walls by using special roots that grow out from its stems. These are called aerial roots or adventitious roots, and they work like tiny natural anchors. There are many different types of plants that grow up walls, but ivy is probably one of the most well-known. Ivy climbs
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How do animals migrate up and down mountains? A lot of animals do migrate up and down mountains. This is called altitudinal migration. It is a kind of vertical migration, although the term vertical migration is also used for animals that move up and down through the ocean every day. Animals migrate over many different
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How do warning colors on animals work? Warning colors on animals work by being easy to see, easy to remember, and unpleasant enough that predators learn not to make the same mistake twice. Many animals are either trying to hide from predators or trying to creep up on prey. That is why so many animals
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