When did people start wearing wristwatches? People started wearing wristwatches during World War 1. Clocks had been around for some time before the first watches appeared in the 15th century, in Europe. Several advancements were necessary before clocks could be made small enough to be a watch. Clocks generally worked by using a system of weights […]
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Why does a chicken’s head stay perfectly still when you move its body around? Because chickens cannot move their eyeballs in their eye socket and because they don’t have a vestibulo-ocular reflex. Our heads (humans) are pretty much constantly moving, yet we can see perfectly well. This is all thanks to the vestibulo-ocular reflex which
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Does ABS reduce fatalities in car accidents? Anti-lock braking systems (ABS) have made cars far safer, but they haven’t reduced fatal accidents because of something called risk compensation. Anti-lock braking systems are designed to stop the wheels of a vehicle locking up when the brakes are applied in an emergency. If the wheels on a
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How does a smoke detector work? There are two different types of smoke detectors, and they respond to different types of fires. There are photoelectric smoke detectors that respond to smoke from smoldering fires and there are ionization smoke detectors that respond to smoke from flaming fires. Photoelectric smoke detectors have a chamber that has
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When did the last woolly mammoth disappear? A population of woolly mammoths survived on Wrangel Island until about 2000 BC, about 500 years after the Great Pyramid of Giza was built. Woolly mammoths appeared in Siberia about 700,000 years ago. They were the same size as a modern African Elephant: up to 3.4 m at
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How long have humans been using rope? Prehistoric man started using rope over 50,000 years ago. Rope is an incredibly important invention in the history of humankind. We might not think about it now because we have nails, screws, Velcro, wood, solder, and a hundred other ways to keep things together, but prehistoric people only
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Why is New York called New York? New York is called New York because it was named in honor of the British Duke of York. Before European people colonized the Americas, the Algonquian speaking Native Americans lived in the area where New York is now. The Algonquian speaking people were the largest indigenous group in North
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How much maple tree sap do you need to make 1 liter of maple syrup? It takes about 40 liters of sap to make 1 liter of maple syrup. Maple syrup is made by taking the sap from sugar maple, black maple, or red maple trees. The trees are tapped when they are about 30
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Why are steam burns worse than boiling water burns? Steam burns are more severe than boiling water burns because steam goes through a phase change when it touches your skin, and it can penetrate your pores. Water is made up of molecules and molecules are made up of atoms. These atoms each have electrons and
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How did the neck verse save people from being hanged in England? The benefit of clergy was known as the neck verse and it was an English law that allowed people to escape hanging if they could memorize Psalm 51:3. Latin: “Miserere mei, Deus, secundum misericordiam tuam; et secundum multitudinem miserationum tuarum dele iniquitatem meam.”
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