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. […]
#1356 How does sunscreen work? Read More »
Why does ice float? Ice floats because it is less dense than liquid water. Ice is one of the very few liquids that expand when they are frozen. The majority of materials contract. Ice floats on water because of its density. A less dense material will always float on a more dense material. The density
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Is alchemy actually possible? With today’s technology, alchemy is technically feasible, but making a lot of gold would require more energy than is practical. These days, we associate the word alchemy with the attempt to change base metals, such as lead, into gold, so called precious metals. However, that is not what alchemy is. Alchemy
#1318 Is alchemy actually possible? Read More »
Why is an atomic clock so accurate? Atomic clocks are accurate because atoms oscillate at a stable and predictable frequency. All clocks work by using the number of movements of something to calculate the passage of time. They do this by knowing how many movements of something equal a second and working from that. Mechanical
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What is junk DNA? Junk DNA is DNA that doesn’t seem to do anything. It is not part of our coding DNA. DNA is in the cell nucleus of all of our cells. DNA stands for deoxyribonucleic acid. The deoxyribo part is sugar. The nucleic acid part is a long chain like molecule. Inside the
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What is the difference between conduction, convection, and radiation? The difference is that they are three different ways of transferring heat energy. I think we first need to look at what heat is. Heat is defined as “the transfer of thermal energy from one physical system to another system, or from one region in a
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Could a perpetual motion machine be possible? No, because any perpetual motion machine would break the laws of thermodynamics. The definition of a machine is a device used to perform a task. Any perpetual motion machine has to be able to perform work to be a machine. There are a lot of people that say
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Does the ozone layer still have a hole? Yes, the ozone layer does still have a hole, although it is slowly repairing itself. The ozone layer is not very thick, but it is vital to our survival on this planet. We talk about a hole in the ozone layer, but it is not an impenetrable
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What is Prince Rupert’s drop? Prince Rupert’s drop is a small, tadpole-shaped glass bead that is incredibly strong but incredibly fragile. Prince Rupert’s drops have been around for a long time and there is some thought that they were first discovered by Roman glassmakers two thousand years ago. They were first brought to Great Britain
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Why are some materials brittle? Materials such as glass and ceramics are brittle because their atoms are held together by strong bonds that cannot slide past each other. If you have ever dropped a jar of something on a hard floor, you will know that glass is very brittle and shatters when impacted. Or, if
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