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The difference between a fluid and a solid is the following: Fluid's have zero shear modulus, so they can't carry a shear force, but solids have non-zero shear modulus, so the can carry shear force. Fun little way to visualize this: Let's say we line up a bunch of second graders on rectangular grid. Now we push one of the students along one row. That ...

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Treating a medium as continuous (which works for our purposes), for sound to travel through the medium the motion of one unit of it has to affect the motion of the next unit, and so on and so on. Sound in a gas or liquid does this by varying pressure: the air pressure next to a speaker suddenly increases, pushing a unit of air outwards towards the adjacent ...

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According to this website: Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves...Through solids, however, it can be transmitted as both longitudinal waves and transverse waves. This means that through most forms of matter (gases, plasma, liquids), such as water, or the air, sound travels as ...

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In the first case I get points where there is an oscillation in time, while in the second one, as stated, the points "do not oscillate": where there is a minimum, that minimum stays there in time and the same happens for maxima. This is not true. There is identical time dependence, of frequency $\omega$, in both situations; as I said in my answer to your ...

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From the wiki article on the sun's radiation: Solar irradiance spectrum above atmosphere and at surface. Extreme UV and X-rays are produced (at left of wavelength range shown) but comprise very small amounts of the Sun's total output power. You ask: My Question is, why exactly does the intensity vanish below 240 nm ? If i look at the plank's law, ...

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In a polaroid type of polarising material the molecules are aligned in the same direction throughout the sheet when the material is manufactured. Their electric dipoles are therefore also aligned and thus absorb photons whose electric field is parallel with the electric dipoles (to an extent that depends on cos(theta)^2 where theta is the angle between ...

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There are two effects at work here to form the Color Afterimage. The blue light stimulates the S-type cone cells most, and they simply "tire out". Local supplies within the cell of ATP become run down, and the cell cannot therefore signal as often or as effectively. When you looked away into a more "balanced" light, white light that would normally fire all ...

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