How do vending machines check money? They check notes with cameras or photocells. They check coins with electromagnets and light sensors. They are much more able to spot fake notes and coins than they used to be. Early vending machines didn’t need to read banknotes because nothing that expensive was sold from them. The very […]
#950 How do vending machines check money? Read More »
What is a rebreather? It is an underwater device that allows divers to reuse the air that they have breathed out, thereby being able to stay underwater much longer. Most people, when at rest, breathe about 12 times a minute and take in about half a liter of air each time. If we are breathing
#949 What is a rebreather? Read More »
How high can birds fly? A Ruppell’s vulture was hit by a plane at 11,300 meters. The bird was identified by the feathers after the plane landed. There may be other birds that have flown higher, but they have not been encountered, so this is probably the record. There are three things that dictate the
#948 How high can birds fly? Read More »
Is cocaine natural? The main ingredient in cocaine comes from a natural plant, but it needs to be processed. Cocaine is a stimulant taken from the leaves of the coca plant. The Coca plant grows in South America, on the lower slopes of the Andes. Because it is such a valuable crop, cultivation has spread
#947 Is cocaine natural? Read More »
What happened to Kaiser Wilhelm? He was given asylum in the Netherlands, where he lived until he died in 1941. Wilhelm became Emperor of Germany and King of Prussia in 1888. Germany was not a unified country until after the end of World War 1. What we know now as Germany was a collection of
#946 What happened to Kaiser Wilhelm? Read More »
How is silk made? It is made from the cocoon of the silkworm. Silk is a natural material that has been around for over 5 thousand years. Silk was first made by the Yangshao culture in China in the 4th millennium BC. One legend has it that an Empress was drinking tea and a silkworm
#945 How is silk made? Read More »
What could the 10 plagues in the bible have been? Assuming they actually happened, they could all have rational explanations. However, the evidence shows that they were not a real event. The ten plagues appear in the Book of Exodus in the Old Testament. The story is that the Israelites were enslaved by the Egyptians
#944 What could the 10 plagues in the bible have been? Read More »
Why can grasshoppers jump so high? They can store energy in their exoskeleton and release it like a spring. Grasshoppers are not all the same. They are a small group of insects in the Caelifera family, which contains about 12,000 species. Locusts are grasshoppers and they belong to this family, and many other insects that
#943 Why can grasshoppers jump so high? Read More »
What is a failed state? It is a state that can no longer control its own security and does not have control over its territory, borders, economy, and people. The expression “failed state” hasn’t been used since 2014 because it has the nuance that a state cannot be saved. The correct expression is “Fragile State”.
#942 What is a failed state? Read More »
What is asbestos? Asbestos is a material made of lots of mineral fibers. It can be woven into shapes and it is fire-resistant. Asbestos is a natural mineral that is mined and then processed. There are six different types of asbestos, and they are divided into two categories: amphibole and serpentine. The fibers in the
#941 What is asbestos? Read More »
