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What you see is the escape of dissolved gases in the liquid. Water in a cup in a microwave heats fairly uniformly; by contrast, if you heat on a stove, you hear the water "sing" because you get local boiling of the water that is right next to the wall being heated. During the "singing", dissolved gases are driven out (and they don't really re-dissolve - but ...


4

Paper is made of many, many tiny fibers. When you wet a piece of paper, those fibers absorb water and swell up. As they dry, the relaxed fibers don't go back to exactly where they started. Some will have shifted or "untangled", moving out of the plane of the original paper. So yes, the paper actually does become slightly bigger because the fibers have ...


4

To a reasonable approximation steam at 100°C can be treated as an ideal gas. The molar volume of an ideal gas is 22.4 litres, so at 0°C (273K) and one atmosphere 18g of steam occupy 22.4 litres or in more useful units 0.018kg occupy 0.0224 cubic metres. You can work out the volume at 100°C (373K) using Charles' Law, and then calculate the density of steam at ...


2

As a physics problem in a textbook, you could get somewhat close. Both the water and the steel have a heat capacity that relates the amount of temperature rise that would accompany an input of energy. If you make a few assumptions, you can relate the two. The problem with a real-world application is that those assumptions may be far from valid. The two ...


2

The one that absorbs more heat from you will cool you more, and seem colder. But it isn't entirely straightforward. If you pour water in your hand, water will flow to fit you. An ice cube will not make as good contact. Water in contact with you will warm. It can then flow away and be replaced by fresh cold water. Ice doesn't flow On the other hand, Ice ...


2

Others have explained the physics. I just want to add that those of us with low body fat can become negatively buoyant at the surface if we breath out and empty our lungs. I can sink down and sit on the bottom of a swimming pool. So it is very possible to dive to a depth where you have negative buoyancy but what depth that will be will depend on the density ...


2

I will focus on just a little bit of one of your questions - the relationship between compressibility, density and pressure - and per my comment, recommend that you narrow down the scope of your question. As you know, in a gas we experience "pressure" because molecules hit the walls of the containing vessel. When I double the number of molecules in the same ...


2

First up thanks to all who took an interest especially @irishphysics who stuck with the question for some time. It turns out that the phenomena was analysed and solved by Lord Kelvin and is known as the Kelvin wave pattern. The pattern itself is the result of a spreading pressure wave which manifests itself as the curved diverging wave crests (the ones I ...


1

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 ...


1

The air in the freezer is a poor conductor of heat. The greater surface area of the porous paper along with its heat conducting water allows it to act as a heat sinc. It transfers heat from the liquid to the glass or aluminium and then to the water in the paper which sheds the energy by conducting it to the surrounding materials such as the air and the ...



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