Do submarines still use periscopes? Yes, submarines do still use periscopes, although they now combine them with many other high-tech sensors as well. At its simplest, a periscope uses two angled reflectors to send light down a long tube. A basic periscope looks a bit like a straightened “S.” The top opening faces whatever is […]
#1606 Do submarines still use periscopes? Read More »
How does bleach kill microbes? Bleach sterilizes by oxidizing molecules in the cells of germs, viruses, and bacteria, killing them. When something is oxidized, electrons are taken away, which disrupts the function of important molecules. Rust is a familiar example of the kind of damage oxidation can do. There are two main types of bleach.
#1605 How does bleach kill microbes? Read More »
What is Monosodium Glutamate? Monosodium Glutamate (MSG) is a salt used to add flavor to food. MSG is the sodium salt of glutamic acid. Glutamic acid is an amino acid that occurs naturally in lots of foods, such as tomatoes, cheese, mushrooms, and seaweed. In foods, glutamic acid often loses a hydrogen ion and becomes
#1604 What is Monosodium Glutamate? Read More »
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
#1603 How does a tunnel ventilation system work? Read More »
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
#1602 Do all animals have imprinting Read More »
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,
#1601 What does E = mc2 mean? Read More »
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
#1600 Which of the Seven Wonders of the Ancient World still exists? Read More »
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
#1599 How do fish ladders work? Read More »
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
#1598 Why is someone who crosses a picket line called a scab? Read More »
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
#1597 How did John Harrison’s clock allow for longitude to be used? Read More »
