What is escape velocity? Escape velocity is the minimum speed an object needs for it to be able to escape the gravitational pull of a celestial body. Everything in the universe has gravity. Even dark matter has gravity, which is how astronomers know it is there even though they can’t see it. The gravity of […]
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Why do so many borders in Africa have straight lines? So many countries in Africa have borders with straight lines because there are no landmarks to define the borders in those areas. Along with that, nearly all of the borders were created by the colonial powers. If you look at the borders between countries in
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How does sunscreen work? Sunscreen works by either reflecting the ultraviolet rays back up, or by absorbing the ultraviolet rays. When we go out into direct sunlight, we are coming into a lot of energy that the sun is sending our way. The sun releases energy as electromagnetic waves in a whole range of wavelengths.
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Why is soil pH important? The pH of the soil affects what kinds of nutrients and chemicals can be absorbed by water and then taken up by plants. Some plants like a high pH and some like a low pH. PH is a way of measuring how acidic or alkaline something is. PH stands for
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How do AIDS drugs work? AIDS drugs work by preventing the HIV (Human Immunodeficiency Virus) form being able to multiply. AIDS and HIV are not the same thing. AIDS stands for Acquired Immune Deficiency Syndrome. HIV causes AIDS. AIDS is the late stage of HIV infection and happens when the virus has built up to
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How is nuclear fuel stored in glass? Spent nuclear fuel is not stored in glass. Spent nuclear fuel can be turned into glass through a process called vitrification. The word “vitrification” comes from the Latin “vitrum”, which means glass. We still use the word in some circumstances. The word “vitriol” comes from the same root.
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What is the last common chimp-human ancestor? The last common chimp-human ancestor was probably about seven million years ago, possibly, although there are no remaining fossils of this animal. It is often mistakenly said that humans evolved from chimpanzees, but this is not the case. Both chimpanzees and humans evolved from a common ancestor in
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Who were Rolls and Royce? The Rolls and Royce of Rolls-Royce Limited were Charles Rolls and Henry Royce. Rolls-Royce is a hugely famous brand name, but it is actually not a single company these days. The company has two parts. The largest part is Rolls-Royce plc, which is the part of the company that makes
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How can you fire through a propeller? Not a lot of planes did this, but the only way a plane can fire through a propeller is by synchronizing the gun and the propeller. By the start of World War 1 in 1914, powered flight had only existed for 11 years. On December 17th, 1903, Orville
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What happens to the human body in space? Astronauts in space lose bone mass and their muscles weaken. Their blood volume decreases, and their heart can shrink. They are exposed to radiation, and they may have mental changes as well. People have only been going into space for 64 years. The first person in space
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