# Tag Info

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What is meant by a “change in volume of a system”? "Change in volume of a system" means "change in volume of a system", not anything else. System is a hypothetical concept. There is no specified system before we define it. We ourselves choose and define system. When someone talks about a system defined by himself/herself, he/she talks about that system not ...

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My essay Misconceptions about Virtual Particles explains in detail the difference between the popular science view of virtual particles popping in and out of existence and the physical science view of virtual particles as useful (but literally virtual) imagery for talking about complicated integrals for the computation of scattering amplitudes. From the ...

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The vacuum does not pull, it is an illusion, what happens is the molecules on the air outside hit the piston and produces a force inwards, and because on the inside there is very little gas (or none if there were a perfect vacuum) there is no force to stop the piston prom moving inwards.

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In a word, no. Getting into space is a matter of achieving enough velocity to overcome the Earth's gravitational influence, not about buoyancy. You can use buoyancy to get to the edge of the Earth's atmosphere, not beyond. We don't fill a rocket with helium so it'll float into space, nor do we use balloons to get beyond the edge of the Earth's atmosphere.

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Phenomena is called Cold Welding The reason for this unexpected behavior is that when the atoms in contact are all of the same kind, there is no way for the atoms to “know” that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin surface layers of contaminants in between, the ...

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Vacuum or pressure is quantified in terms of bar or torr. 1 bar or 760 torr is roughly one atmosphere and in terms of vacuum measurement 1 mili-bar is taken as almost equal to 1 torr. at 1 bar pressure and at room temperature the number of atoms per cc is ~$2\times 10^{19}$. The number of particles per cc in vacuum can range from $10^{-4}$ to $10^6$. The ...

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OK this is pretty simple. When the soup cools the pressure drops below the outside pressure and seals. That was said already. But usually a soup container in a traditional bento box has a little push button valve on top that when pressed releases the vacuum within the container. Be sure to use the right container for your soup or look into getting one ...

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