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The effect you describe is really just the "draw" of a chimney - hot air rises because it is less dense than cooler air. The weight of the column of air inside the chimney is this less than the weight of the column of air it displaced (Archimedes' principle) and it experiences an upwards force. Again, because air is light you only need a little bit of force ...


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Thank you very much for taking time to answer my question, I appreciate that greatly and would like to supply the background to my question Many years ago I was working on a construction project in the Kalahari Desert when I saw something unusual. In the works yard. There was a length of straight galvanised thin wall steel pipe standing vertically, about 15 ...


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Okay, so perhaps the easiest approach I can think of relates to basic fluid flow. If we ignore gravity (and other external/internal forces) for the moment, then we can describe the fluid motion as: $$ \frac{d \mathbf{v}}{dt} = -\nabla P $$ where $P$ is a scalar pressure. In an ideal gas, this can be written as: $$ P = \frac{3}{2} n \ k_{B} \ T $$ where $n$ ...


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Brionius has the right answer, but there is more to be said. Water at room temperature in air will slowly evaporate. Water at room temperature in a vacuum will boil, as is shown here. So these mini torpedos can prevent damage to chemical bonds. Water molecules are polar. The O's are a little negatively charged. The H's are a little positive. The H's and ...


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In fact, they do!! Watch what happens to an ice cube that is left in the air... trillions of particles of its exterior are torn out of their stable arrangement, and soon they cascade down the sides—a microscopic waterfall! So in this case you are right, but it is just the very exterior surface of an object that is exposed to the air and thus affected ...


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Another way of looking at this is that things that would be destroyed by the environment (be it heat, light, etc) have already been destroyed (like ice on a hot summer day). The things that you see around you are the ones where the bond energy was high enough that they survived.


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Things actually do get destroyed by what those air molecules pick up and throw around. Take look at this example [image from here: http://en.wikipedia.org/wiki/File:Arbol_de_Piedra.jpg ] Just like their bigger sized brothers, it's the load of those mini-torpedos that brings the destruction.


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When you say "why aren't things being destroyed", you presumably mean "why aren't the chemical bonds that hold objects together being broken". Now, we can determine the energy it takes to break a bond - that's called the "bond energy". Let's take, for example, a carbon-carbon bond, since it's a common one in our bodies. The bond energy of a carbon-carbon ...


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A blimp or zeppelin can fly without using energy. If it's engines are turned off, it can travel with the wind. I think you're asking - can it be done while having control over where you go, or how fast, while using arbitrarily little fuel? This is an old idea, and it has been tried. It is possible, but so far not practical. To find out more, just Google ...


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The Solar Impulse flies without fuel, so the answer to the question in your title is yes. In theory you could design an airship that used very little energy. It would have to become lighter than air to take off, say by shedding some ballast, fly to where it is going, and become heavier or catch a landing rope to land. If that sounds like a helium balloon, ...


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It's a hoax. Think of a submarine—it can go towards and away from the center of the Earth due to gravity and buoyancy respectively, but it cannot do this without changing its density. And it cannot change its density without fuel. From the U.S. Office of Naval Research: To descend, water is allowed to flow in through the bottom of the submarine: To ...


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Yes. a wave created with a certain frequency in the water remains the same even if the medium is changed. The only thing that is important in here is the amplitude of our wave. When the sound wave from inside of water hit the surface, some of the wave reflect back into the water and a lower amplitude wave is continued in the air. so the energy of the wave ...


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Is it possible that when you mean an absence of air, you mean to say an absence of moving air? If so, then there is a difference to how fast clothes will dry. If there is no moving air, then the only considerable means of heating up the clothes and the moisture on the clothes is the thermal radiation from the sun. The radiation heats up the moisture and it ...


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I think when you say "no air" you mean "no wind" In modern greek too "air" can mean "wind" and and also the content of the atmosphere. So if you hang clothes in the same sun but with no wind to supply convection, the clothes will try slower than when a wind is blowing, due to convection. Convection replaces the saturated air close to the clothes with ...


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Disclaimer before I get started: A perfect vacuum is impossible. As I answer your question, I will take your use of the word "vacuum" to mean "a chamber with an air pressure arbitrarily close to 0 Pa." When I use the word "vacuum" in my response, I mean the same. Your clothes don't need the air in order to dry, and in fact, will dry more quickly. ...


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I don't understand the difference between the first and the second question, but the answer is "No, you don't need air for the clothes to dry". In fact, it will dry faster if in vacuum, because the water will start to boil in zero pressure, even if the temperature is not 100º C. In fact, at zero pressure, water cannot exist in liquid, but will evaporate if ...


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Your clothes would dry very quickly in a vacuum, assuming that the temperature is still one that one would find on earth. This is because the water would boil out of your clothes. On earth normally, boiling takes a lot of heat energy. This is because of the air pressure. In your scenario there is no air pressure. so the water will boil easily.


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No air means no vapor too. So without air your clothes will dry more easily, because the wetness will vaporize more easily.


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I think: Without air arround, you have some kind of a black body. Depending on the distance to the sun your body will reach a constant temperature. If this temperature is above the boiling point, you wet clothes will become dry. Because the gravitational attraction of your clothes is much smaller than the pressure of the water vapor. Thus the water molecules ...


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A reasonable sub woofer at sound power level of 130 dB would produce pressure fluctuations of 60 Pa. Compare this to the ambient pressure of 100'000 Pa and you will see that related temperature fluctuations would be negligible. It extinguishes fire because it pushes the air back and forth. For the small fire in this video you could take a small air blower ...


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you can simply use the formula as Velocity = 331.4 + 0.6*Temperature + 0.0124*Relative_Humidity Temperature is in Celsius Degrees Relative Humidity can be measured by sensors in %age



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