History of Science

Find questions about the origin and important events that led to the development of the different Sciences.

Asked in History of Science, Physics

Why does a ball fall to the ground?

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Because space is extremely curved in proximity to the huge mass of the earth. Or because the force of gravity causes attraction between the ball and the Earth. It depends on which aspect of physics you are using.
Asked in History of Science, Scientists, Louis Pasteur

Who was Louis Pasteur and what did he do?

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Louis Pasteur was a 19th-century biochemist whose work with germs and microorganisms opened up whole new fields of scientific inquiry, aided industries ranging from wine to silk, and made him one of the world's most celebrated scientists. Louis Pasteur was born on 27 December 1822 in Dole, Jura, France. He was to become known as the founder of microbiology. Pasteur was the one who discovered the role of bacteria in fermentation. In 1857, through experimentation and research with bacteria, he determined that certain microorganisms contaminated fermenting beverages. He used this knowledge to develop a process whereby liquids such as milk were heated to kill all bacteria and moulds which were already contained within them. This process became known as pasteurisation. The first test of pasteurisation was completed by Pasteur with the assistance of Claude Bernard, on 20 April 1862. Pasteur then recognised that infectious diseases are caused by microorganisms, and his research soon led others to investigate sterilisation, disinfection, vaccines, and eventually antibiotics. Pasteur created and tested vaccines for diphtheria, cholera, yellow fever, plague, rabies, anthrax, and tuberculosis. The rabies vaccine was first tested on a nine-year-old boy named Joseph Meister, on 6 July 1885. Meister was bitten by a rabid dog, and was subsequently treated by Pasteur with a rabies virus he had grown in rabbits but weakened by drying, a treatment he had earlier tried on dogs. The treatment was successful and the boy survived without ever developing rabies. Joseph Meister later went on to become a caretaker at the Pasteur Institute. Pasteur was subject to strokes from the early age of 46, and eventually died in 1895 from complications resulting from these strokes.
Asked in Physics, History of Science, Isaac Newton

Which law proved that newton's gravity law is wrong?

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Newton's Law of Gravity is not wrong, in macroscopic scale and at relatively low speed, it predicts the movement of objects accurately. However, objects at microscopic scale near the speed of light will have to take into account time dilation, and General Relativity helps describes these.
Asked in Chemistry, History of Science

Why is dry ice disappearing a chemical change?

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It isn't. Answer --> It is an example of phase change and thus a physical change. Not a chemical change
Asked in History of Science

Why is boiled water tasteless?

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When you boil water, you remove some of the impurities in the water -- specifically, those that will evaporate at the temperature of boiling water. These impurities add a slight flavoring to the water. Boiled water is not always tasteless. Salty water still tastes salty after being boiled. Try it.
Asked in History of Science, Periodic Table

Who created the modern-day periodic table?

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Henry Moseley. Dmitri Mendeleev first proposed the periodic table be sorted based on atomic weight. After the discovery of protons, Henry Moseley reordered the table based on atomic number. That is the structure we use today.
Asked in History of Science, Bodies of Water, Lakes and Rivers, Soaps and Detergents

What does detergent do to lakes?

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detergent itself: practically nothing. however many commercial detergent blends include phosphates: these can fertilize algae growth, reducing oxygen in the water, and killing other aquatic life.
Asked in Geology, History of Science

How does weather affect rocks?

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it breaks it down (weathering) and carries it away (erosion) with water, ice, and wind.
Asked in Physics, History of Science, Electrical Engineering

How back emf helps in energy conversion in a motor?

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.. I am an engineering student and during the past few days i was searching on the net to clarify my doubts on "motors".So i came across an article and on reading one part of it a doubt arosed in my mind. Q1) "To take a practical example, an electric motor running under no load uses very little power. If the motor were frictionless and superconducting, it would use no power. This is because the back emf opposes the imposed voltage." This was the part of the article.My doubt is that If the motor was frictionless and superconducting will it rotate and produce mechanical energy?? Q2)Can you tell me how the electrical work done by the applied voltage in overcoming and causing current flow against back emf is possible?? Practically i know that when someone is pushing me in one direction in order for me to oppose it i need to give an equal and opposite force.That is a push is required to oppose a push.. So using this idea in motors our applied voltage must do an equal amount of work against this back emf.Hence our applied voltage must provide an equal amount of electrical energy to oppose the electrical energy produced by back emf..So if this was the condition can you tell me how this back emf aids in converting electrical energy to mechanical energy??? Q3)What will happen if there was no back emf?? <<>> A1) if the motor is frictionless and superconducting, it will rotate with the generated voltage equal to the supply voltage, with zero current flowing, in a steady state, with a fixed amount of kinetic energy. However, to reach that state it has to run up from stationary, and during that time it will absorb energy from the supply (a frictionless motor with no resistance will do this in zero time, taking an infinite current until it reaches the steady state). The generated voltage or back emf is proportional to speed, and the current is equal to the supply voltage minues the generated voltage, divided by the armature resistance. The angular acceleration is proportional to the torque, and the torque is proportional to the current. That gives you all the information you need to work out what is going on. A2) The supply is providing power by raising electric charge through a potential gradient, and the charge then flows down the potential gradient in the load, doing work (or generating heat) as it does so. Imagine you are sitting on a trolley and someone is pushing you, and ignore friction. Force equals mass times acceleration, so your acceleration is equal to the force divided by the total mass of you plus the trolley. At the point of contact you are pushing back on the other person, but this force is balanced by your acceleration. The work done by the pusher, force times distance, equals the kinetic energy of you and the trolley 0.5 times mass time speed-squared. The impulse provided by the pusher, force times time, equals the momentum of you and the trolley, mass times speed. A3) You can ensure there is no back-emf by locking the armature of the motor (put a screwdriver in to stop it rotating). In this condition the current equals the supply voltage diided by the armature resistance.
Asked in History of Science

What is the roman word for death?

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Mors is the general term. Obitus is for death from old age. Decessus or Excessus are other ones.
Asked in History of Science, Elements and Compounds, Radium

Is the radium named after someone?

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No, the name radium is derived from the Latin language word radius, equivalent to radiation.
Asked in Astronomy, History of Science

What is the source of heat and light for all the plants?

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The sun is the source of heat and light for plant-life.
Asked in History of Science

How is Potemkin pronounced?

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My Russian dictionary has a diaresis over the e - Потёмкин - and being of the Soviet era, gives the translation as "the dark one", which presumably means Satan. The diaresis converts the e (ye) to yo, which is always stressed in Russian. The o in the preceding syllable, being unstressed, degrades to a as in father. The complete word is thus Pa(h)-TYOM-kin Note that the y is sort of absorbed into the t - a process called palatisation, which therefore makes a sound closer to the English ch. We might write it as PaCHOMkin Note that these remarks are based solely on the uncapitalised word in the dictionary. As a name, it might be something different. But I think calling a (pre-revolution) battleship Satan is more than probable.
Asked in History of Science, Microbiology, Scientists

Who is josephine pasteur?

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she is the sister of Louis pasteur who created pasteurization, the rabies vaccine, and lots of other things
Asked in Chemistry, History of Science, Elements and Compounds

When was francium discovered?

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Radon (element #86) was discovered in 1900. Francium (#87) was discovered in 1939. Francium is the second rarest naturally occurring element. It is also one of the most reactive elements known to man and has a high isotopic instability, with a half life of about 22 minutes. Francium is a part of the Alkali metals group, which are all quite reactive with water and air, Francium being the most reactive. Francium will react explosively upon contact with air, and you wouldn't want to be there if it came into contact with water.
Asked in History of Science, Gravity

How much do objects accelerate as they fall?

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If the objects are under free fall near the surface of the Earth, then they are under uniform acceleration due to gravity whose magnitude is 9.8ms-2 . In general, on the surface of a planet of mass m and radius r the acceleration due to gravity is Gm/r2, where G is Newton's gravitational constant.
Asked in History of Science, Digestive System, Muscular System

What term describes a series a wavelike contractions of the smooth muscles in a single direction?

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The wavelike contractions of the smooth muscle in the gastrointestinal system are called peristalsis. The purpose of peristalsis is to push boluses of food along the gastrointestinal tract. This is achieved by the waves of contractions in the smooth muscle followed by relaxation of the muscles, pushing the bolus (ball of food) a bit further along the digestive tract with each contraction. These contractions move food or chyme through the esophagus, and intestines. The same contractions also move urine down the ureter to the bladder.
Asked in History of Science

Is urine drinkable?

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You can drink it, it's sterile, and as long as it's fresh, and you don't have any UTIs bacteria free. It is, for the most part completely safe. That said, it is all the stuff your body didn't want first time through, and probably won't taste very pleasant. I imagine it would be warm, salty and acidic tasting. "Clear" pee is mostly water, and yes, it's true the more you drink, the more diluted the stuff your body is looking to get rid of will be, but my understanding of the body is that it will never be pure water. The human body is not very efficient, and some people even claim drinking urine is of some medical benefit, in that it gives your body a second chance to get some of the "good bits" which were unnecessarily filtered first time, though this is at best speculative. You would mostly be very safe to do so, if you want, though it is a hard one to recommend to anyone. If you were stranded, without water, and on the verge of dehydration, then yes, go right ahead (though if you were on the verge of dehydration, you wouldn't be peeing anyway, so you would have to start storing it early on in this situation). But in the civilized world, with water on tap and better drinks readily available, it's hard to know why you would want to. If you're gonna do it though, my suggestions would be... 1. Don't drink your first pee of the day, or the one you've been waiting for hours to "relieve yourself" of. It'll be more concentrated, stronger tasting and harder to stomach, and has more chance of containing "nasties". 2. Don't do it if you have any reason at all to believe you may be suffering any infection "down there". Don't run the risk of spreading bacteria around your body. If the smell or colour are particularly strong, or different from normal, you may have an infection, see a doctor. If there is any pain peeing or blood in the urine, you have bigger problems than drinking your pee, SEE A DOCTOR. 3. If you have drunk alcohol, or taken drugs recently, don't drink your pee. Unprocessed alcohol and drugs could, in theory, be present in the urine, and could cause you problems. Also, don't think drinking pee is a "free high" it's not, the compounds in the alcohol or drugs could be significantly changed while in your body and could do you serious damage. Your body is flushing them out for a reason. 4. Don't be tempted to refrigerate it to make it easier to go down. While fresh pee is sterile, it can grow bacteria quickly. If you must drink it, do it while it's fresh. It'll be warm, and probably not pleasant, but that's the price you pay. 5. Drink lots of water before trying it. As you said, the more water you drink the more diluted it'll be, and therefor the easier to drink it'll be. Just because it's clear though, don't expect it to taste just like water, though have no frame of reference for it, i imagine it probably won't. Don't set your sights too high. I repeat, it probably won't be pleasant. 6. Under no circumstances be tempted to drink someone else's pee. It should go without saying, yet i feel i should say it (you're considering drinking pee for a friend, so who knows where it could lead) it has all the above problems (infection, as well as added STI issues, alcohol, drugs, no way of knowing how diluted it will be) with the added problem of not knowing whether they are telling you the truth about these things. 7. Ask yourself... is this really something i want to do. Why are you even considering this? although some people enjoy it, or have particular sexual enjoyment out of this sort of thing if you're doing it just because your friend told you to, is it really worth doing? What really do you stand to gain from it? If you don't have a good answer to that, then don't do it. In fact, my recommendation to most people is DON'T DO IT. Really, there isn't any good reason to.