How does a tunnel ventilation system work? A tunnel ventilation system either uses evenly spaced air vents to pull in air or powerful fans to push it along. They also use extractor fans to remove the car emissions, and they rely on the piston effect of vehicles entering the tunnel. As tunnels get longer, designers […]
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Do all animals have imprinting? No, not all animals have imprinting, but a lot do. Imprinting is where a newborn animal learns to follow its protector as soon as it is born. When the animal is born, it imprints the closest animal, usually its mother, into its brain and then follows that animal exclusively. The
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What does E = mc² mean? E = mc² means that mass and energy are two ways of describing the same physical thing. In everyday life, mass feels like “stuff” and energy feels like “activity,” but Einstein showed that they are connected. If a system loses energy, it also loses mass. If it gains energy,
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Which of the Seven Wonders of the Ancient World still exists? The Great Pyramid at Giza is the only one of the Seven Wonders of the Ancient World that still exists. The Great Pyramid of Giza is both the oldest of the Seven Wonders and the only one still standing. It was completed in roughly
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How do fish ladders work? Fish ladders have a series of stepped pools that allow fish to swim back up a river and climb over any human-built obstacles that might be in their way. The idea is to mimic the natural riverbed. Salmon are the most commonly known, but there are many different kinds of
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Why is someone who crosses a picket line called a scab? The insult goes back to the 1500s, when “scab” had come to mean a low, mean, rascally person—a scoundrel. Strikes themselves are far older than most people assume. One of the earliest recorded strikes happened in Ancient Egypt in 1152 BC, when artisans of
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How did John Harrison’s clock allow longitude to be used? John Harrison’s clocks were the first clocks that worked accurately on ships. To calculate longitude, it is necessary to know the time difference between where the ship is and the place it left from. That is only possible with a clock that can keep accurate
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What is a fly-by-wire system? A fly-by-wire system is a way of controlling a plane with electronics rather than with manual flight controls. It is called “fly-by-wire” because all of the pilot’s input is transmitted along electrical wires. The opposite of fly-by-wire controls is mechanical or hydraulic controls. These days, passenger planes and large planes
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How do supermarkets employ psychology? Supermarkets employ psychology by manipulating your senses, tracking your route through the store, understanding where you look, shaping how you feel, and knowing when you are most likely to buy something. Supermarkets appeared at the beginning of the 20th century. The very first supermarket was the Piggly Wiggly in Memphis,
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How does a building sprinkler system work? A building sprinkler system is a network of pipes and sprinkler heads that are activated by heat, not smoke. A sprinkler system is fairly straightforward. A network of water pipes is laid through the building, usually above the ceiling. At predetermined distances, a sprinkler head sticks through a
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