Why are katana blades curved? They are curved to make them more efficient at cutting. Katana are long, curved swords from Japan. Their name “katana” means one-sided blade. “Kata” means “side” and “na” means blade. Many swords are double-sided because it allows them to be more effective when thrust. They can also be used to […]
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What makes rain smell? A combination of plant oils, bacterial spores, and ozone. Everything always smells very fresh after a rainfall and there is a word for it. Merriam-Webster defines petrichor as, “a distinctive, earthy, usually pleasant odor that is associated with rainfall especially when following a warm, dry period”. The word was invented by
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How does dry cleaning work? Clothes are soaked in a water-free liquid solvent. Dry cleaning is a way of washing clothes without water. At home, all of us wash our clothes in the washing machine using some kind of detergent and water. Inside the washing machine is something called an agitator. This is a drum
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What is in toothpaste? It usually has fluoride, abrasives, flavors, humectants, and detergents. So, what do all of these things do? Fluoride is a naturally occurring mineral. It can be found in most places on Earth, and it is also present in our bodies. Our bodies use it to strengthen our bones and teeth. Fluoride
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By Pablo Picasso – wordpress, PD-US, https://en.wikipedia.org/w/index.php?curid=38782663 What is cubism? Cubism is an art form where the artist tries to show an object from multiple viewpoints at the same time. Pablo Picasso is credited with inventing cubism in about 1907, but he wasn’t the only artist experimenting with shapes, he was only the most well-known
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How long does a 747’s runway need to be? A Boeing 747 airplane needs a runway that is at least 2,300 m long to land and over 3000 m to take off. However, this is a difficult question because there are many variables that come into play when determining the necessary length of runway for
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Why are there many different types of screw head? The different types of screw head allow for different amounts of torque and for use by different machines. There are over 30 different types of screw head. Prehistoric people generally joined things together using adhesives. The earliest known adhesive was a tar made from heating birch
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How does body armor work? By breaking up the bullet and removing its kinetic energy. Armor has been around for a long time, but it has always had to adapt to the technology of weapons. In the Bronze Age, they had bronze armor because it was enough to stop a bronze sword blade. Then the
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Can the Mona Lisa ever be sold? The Mona Lisa, by Leonardo da Vinci, can never be sold because it is owned by the people of France. There was a time when the Mona Lisa was owned by a single person. In fact, the painting was owned by a few single people, and could have
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What is & called and why? The symbol “&” is called the ampersand, which actually means “and, by itself, and”. It is also a shorthand version of the Latin word “et”. These days, we use the ampersand as a symbol for “and”. It is also used in programming language. It is not generally acceptable to
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