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How do we know Earth has an iron core? Experts think that the Earth has an iron core because of the way seismic waves pass through the Earth, its overall density, the abundance of iron, our magnetic field, and laboratory experiments. Before we begin, scientists do not know with absolute certainty that the Earth has […]

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

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

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

How does an email filter detect spam? Email filters detect spam by looking at the sender’s information, certain words in the email content, the structure of the email, and user engagement. Thanks to machine learning, they are much more accurate than they used to be. Spam filters have been around since the mid 1990s, which

Why does the Venus de Milo have no arms? They could have been knocked off after the statue was found, but they were most likely lost before the Venus de Milo was buried. The Venus de Milo is probably one of the most famous statues in the world. The whole statue is about 2 meters

When was the first ATM? The first ATM (cash machine) was used on 27 June 1967. It was installed in the Enfield branch of Barclays Bank in London, UK. It was first used by a British actor called Reg Varney, which was part of the publicity to showcase the new machine and persuade people to

What is tofu? Tofu is made from solidified curds of soy milk. The word tofu came into English from Japanese, which, in turn, came from Chinese. The two characters 豆腐 mean 豆 bean and 腐ferment (or rot). Tofu is sometimes called fermented soybean, but it is not actually fermented. The meaning of rot might be

Is brown sugar healthier than white sugar? No, brown sugar is not healthier than white sugar. In fact, they are both pretty much the same thing. We have become very used to assuming that the brown version of a type of food is healthier than the white version. Brown pasta and brown rice are healthier

What is the Big Mac Index? The Big Mac Index is an informal way of working out purchasing power parity between different countries. The Big Mac Index was started as a half-serious joke in an article that appeared in The Economist in 1986. The author, Pam Woodall, was trying to find a way to look