How does a smoke detector work? There are two different types of smoke detectors, and they respond to different types of fires. There are photoelectric smoke detectors that respond to smoke from smoldering fires and there are ionization smoke detectors that respond to smoke from flaming fires. Photoelectric smoke detectors have a chamber that has […]
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Why are steam burns worse than boiling water burns? Steam burns are more severe than boiling water burns because steam goes through a phase change when it touches your skin, and it can penetrate your pores. Water is made up of molecules and molecules are made up of atoms. These atoms each have electrons and
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Why does an elastic band stretch? Because it is made of long chains of polymers that would rather be tangled together than straight. Rubber is famous for its ability to expand and return to its original size without any damage. There are natural rubbers and synthetic rubbers. The English word “rubber” was first used in
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How does antibiotic resistance happen? Bacteria develop the ability to survive an antibiotic, which is then passed on to future generations. The antibacterial power of some moulds has been known about since 1874, possibly even earlier. In 1897, Ernest Duchesne published a paper about the ability of moulds to kill bacteria. Alexander Fleming noticed that
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How do reflexes work? They work by using a reflex arc that bypasses the brain. There are many different types of reflex, but they are generally meant to protect us and to allow us to move around without having to think about everything. Our brains have a limited amount of processing space and if we
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What is the Doppler effect? The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. All energy travels in waves. Some waves, such as sound waves, have to have a medium to travel through and some waves, such as light waves,
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How did the Black Death change society? It ended serfdom and slavery, improved worker conditions, brought a recession, harmed religion, increased antisemitism, improved medical practice, improved women’s rights, and changed the world of art and fashion. There were three major plagues, but let’s look at the middle one, the one that is most famous. It
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How did the Black Death spread? It was spread by people along trade routes. The Black Death is another name for bubonic plague, which is caused by a bacteria called Yersinia pestis. Y. pestis generally lives in fleas that feed on rats. When the flea bites the rat, the bacteria passes into the rat’s blood.
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How does a parachute work? A parachute works because of air resistance. If you jump out of an airplane, presuming you are high enough, you are going to accelerate until you reach terminal velocity. Terminal velocity is the maximum speed an object can attain when falling through a fluid. And here is the point that
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How much blood can you lose? Well, obviously all of it. How much blood can you lose and still function? Depending on your body size, from between 15 to 30%. We have approximately 5 liters of blood in our bodies, but that varies by size. An average-sized female of 165 cm will have about 4.3
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