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This is a comment not an answer, but I can't put pictures in a comment. If Adri agrees this could be edited into his question. If we include the speed of sound and the density on the graph then the result is: All data is from the Engineering Toolbox. The density falls monotonically, so it's the maximum in the velocity that is related to the maximum in ...

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So, it's probably more boring than you're thinking. What has happened is: within a certain speck of substance, if you fire two photons in, they come out together. Now, light is known to behave differently in substances, with the clearest example being refraction: light "slows down" in certain substances like water and glass, behaving a little bit as if it ...

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There is no direct relation between melting point and colour of light produced, it's just that some heat energy is used in breaking intermolecular forces and a part of it is transferred to atoms. So for a higher melting point, a bigger part of energy is used in breaking intermolecular attraction and to change its state of matter. The rest is explained by ...

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The neutron star crust is separated into outer and inner regions. The outer is a crust of neutron-rich nuclei surrounded by degenerate electrons. The inner is similar, but the nuclei are even more neutron-rich and there are degenerate neutrons too. The (qualitative) answer to your question looks at the ratio of electrostatic (Coulomb) energy to the thermal ...

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Piezoelectricity has been found in liquid crystals too, see for ex. see RB Meyer, Physical Review Letters 22, 918 (1969). To show piezoelectricity, a material needs some degree of anisotropy; thus it would hardly be possible to find piezoelectricity in liquids, which are pretty isotropic.

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Piezoelectricity, at least in the usual meaning of the word, arises when you deform a material that does not have a centre of symmetry i.e. there is no inversion symmetry. Liquids are amorphous and therefore (on average) isotropic. This means they are inversionally symmetric (about any point in fact) and therefore will not generate piezoelectricity when ...

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If we were to send a unmannedspaceship through the Sun. What material can survive? A wide variety of materials might survive passing through the outer layer of the sun, but only if the spaceship is big enough, fast enough and has a thick enough sacrificial/ablative shell. If the ship is slow, it doesn't really matter if the hull survives, most stuff ...

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Since the question is rather vague, I will just give you some key points: Debye's model treats oscillation modes of a solid as sound waves (phonons) with frequency $\omega(\mathbf{k})=v|\mathbf{k}|$ ($v$ the sound velocity). As a result, with this model, Debye shows how the heat capacity is directly related to the rate of change of the energy expectation ...

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Graphene is a single atom thick. Some groups have made multi-layer graphene but it's still very thin. It's generally printed on a board so that it doesn't fall apart. Thicker layers are just graphite which is pencil lead.

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I've heard a tragic misconception that blackbody radiation is somehow related to the apparent color of an object. The uninformed reader might read these answers and get the idea that if you paint an object black, no infrared light will come off of it. The key here is that you may reduce the amount reflected - the object would be very cold indeed if it ...

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As far as I know there is no universally agreed definition of material system and I suspect different authors will use the term in different ways. In my experience it means anything that has a non-zero stress-energy tensor, so it includes any distribution of matter and energy. This would include any arrangement of photons. However it would exclude things ...

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From an asymmetrical peak one can determine both a- and c- lattice constant. \begin{align}a=\frac{\lambda\cdot h}{(q_\text{par} \cdot \sqrt3)} \\c=\frac{\lambda\cdot l}{(q_\text{ort} \cdot 2)}\end{align} Where $\lambda$ is the wave length of your X-rays, $q_\text{par}$ (q_parallel) is the peak position alongside the in-plane direction ($q_x$ or $q_y$) ...

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