How long can a nuclear submarine stay underwater? A nuclear submarine can stay underwater for 25 years or longer. The people on the submarine cannot. The submarine can produce all of the water and oxygen they need, but people need more than just to drink and breathe. A nuclear submarine can stay underwater for up
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Why don’t humans have whiskers? We probably lost our whiskers because, as our primate ancestors became increasingly reliant on vision and sensitive, manipulative hands, whiskers became less useful. Whiskers are found in most groups of mammals, although in some species they have become greatly reduced or disappeared completely. Humans are one of the mammals that
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How did astronomers discover dark matter? Strong evidence for dark matter first appeared in 1933, when Swiss astronomer Fritz Zwicky found that galaxies in the Coma Cluster were moving too fast for the gravity of the visible matter to hold them together. The universe appears to be full of something that we cannot measure and
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What was railway time? Railway time was the standardized time introduced by railway companies in several countries to synchronize train times across a country. The steam engine was invented in the eighteenth century and the first steam railway train made its first journey in 1804. 21 years later, the Stockton and Darlington Railway was the
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Why do stars twinkle but planets don’t? Stars twinkle and planets don’t because of how far away they are and the atmosphere. I live in a city and you can’t see that many stars because of light pollution. A while ago I was staying at my brother’s house, and he lives in the countryside. I
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Why doesn’t Venus have a magnetic field? Venus doesn’t have a magnetic field in the same way that we do on Earth, probably because there isn’t enough movement inside its liquid core to produce one. However, that being said, Venus does have a weak induced magnetic field caused by its interaction with the solar wind.
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How did Howard Carter find the tomb of Tutankhamun? Carter was able to excavate part of the Valley of the Kings that had been untouched by other archeologists and discovered the entrance to Tutankhamun’s tomb under some ancient workmen’s huts. Howard Carter had always had a love of Egypt and Egyptology, but he wasn’t an
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How did people discover Antarctica? Antarctica was first discovered by a Russian naval officer called Fabian von Bellingshausen in 1820. However, it is possible that Polynesian sailors reached Antarctica over 1,000 years before. It took a long time to discover the Antarctic because it is extremely difficult to get to. The Arctic was discovered thousands
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They failed for a combination of reasons. Some were overwhelmed by the enormous storm surge caused by Hurricane Katrina, while others failed because of weaknesses in their design and the soft soil supporting them. The flood defenses had also developed over many years rather than being designed as one integrated system. A levee is basically
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Why did feudal levies stop? Feudal levies were a way that kings could raise a temporary military force through the people who they had given patronage to. They stopped because it became an impractical way of conducting warfare. Although not the only country to use it, Medieval England is a good example of this system,
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