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If the phase change occurs at the temperature of interest, then the system can give off a lot of heat without cooling down very much. Thus, melting ice is a great way to maintain something at a temperature around 0°C, and melting paraffin-18-Carbons is good if you are trying to maintain temperature around 20 °C. With a melting point of 28°C, the material ...


3

Assuming the deck doesn't bulge to much at at the sides (as the video suggests), the press exerts work $W$ on the deck acc.: $$W=\int_0^yFdy$$ With $F$ the force exerted by the press and $y$ the displacement. This work is converted to potential energy and stored in the deck. As suggested in the answer to this question, the high pressure is likely to ...


3

If the parts are perfectly solid and they are at equilibrium, then the pressure is constant (ideally). $$q(x,y) = \frac{\int p(x,y)\,{\rm d}A}{\int \,{\rm d}A} =\frac{\text{applied force}}{\text{area}}$$ But if either the floor or the body are ever so slightly elastic then the pressure distribution is given by a non-hertzian contact which concentrates all ...


2

From what I've learnt, this relative strengthening,of cloth when wet, and weakening of paper is due to two factors. First up:The cloth - google fibre structures of cloth, and you will notice that cloth fibers are uniformly but relatively less interlocked, and addition of water causes further attraction via hydrogen bonding. For the paper, it has relatively ...


2

Agarose is a polysaccharide, and like all polysaccharides it is bristling with polar hydroxyl groups. This means the agarose chains interact very strongly with each other by hydrogen bonding. If the solution is heated to a high enough temperature to break the hydrogen bonds (around 90-100ºC) then the agarose molecules behave pretty much like any other ...


2

Dielectric implies nonmagnetic, so the best example of an insulator that isn't a dielectric I can think of is ferrite crystals like yttrium iron garnet, that show a magnetic response while having low or zero conductivity. There are also ferroelectric materials that show a permanent polarization in response to an electric field, and these aren't considered ...


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Comparison of fabrication techniques for hollow retroreflectors describes, in great detail, the two obvious methods: The use of a precision solid prism corner cube as a mandrel to hold the glass plates prior to gluing of the edges. An adjustable set of precision mirror mounts, designed to hold the three plates In both cases interferometric techniques ...


1

Your equation for gas permeation mostly applies to hydrogen, which will dissociate into hydrogen atoms before entering the material. For nitrogen (major component of air), the equation has no square roots. Nitrogen permeation is extremely slow; if the box is welded shut and there are no cracks, then this process will be negligible, even over a 10-year ...


1

Mathematical fractals do not exist in nature. There is however a huge amount of phenomena that behave 'fractally' within a finite range of scales. Take the typical example of the coast of Britain that can be arbitrarily long depending on how finely you are willing to measure it. The link goes to a map where only a portion of the coast is visible. If you use ...


1

For the equation $\epsilon_{ss} = Ce^{\frac{-Q}{RT}}$ it appears that you know $Q, R$ and you have some experimental values (well at least two!) for $\epsilon_{ss}$ and $T$. The usual way to determine the constant $C$ is to take logarithms of both sides giving (as you have noted) $\ln(\epsilon_{ss}) = \ln(C) - \frac{Q/R}{T}$ and to plot $\ln(\epsilon_{ss})$ ...


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The brittleness is caused primarily by interstitial impurities. That's the case of chromium as well as all Group VI A metals. For chromium, the nitrogen atoms are the main impurities.


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In general your relation is $$ \vec{B}(\omega) = (1 + \chi_m(\omega))\vec{B}_0(\omega) $$ or in the time domain $$ \vec{B}(t) =\vec{B}_0(t) + \int\limits_{-\infty}^\infty \chi_m(t,t') \vec{B}_0(t') \;\rm{d}t' $$ Only in the case of instantanous material response, i.e. $\chi_m(t,t') = \chi_{m,0} \cdot \delta(t-t') $, your equation is correct. This already ...


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First of all let me make a correction in your given value of flexural strength of concrete. The value of $16 Mpa$ or $16 N/mm^2$ is about the compressive strength of a typical concrete cube with an edge of 15cm under clear compression. It's tensile strength is about 1/10 of its compressive strength ,so it's about $1.6 Mpa.$ Like concrete ,most materials ...


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There are often several different methods of synthesizing materials, and in lots of cases they arrive at the same result. Sometimes the experiments you want to do will depend on your growth method, though: for instance, the polycrystalline samples you get from solid state reactions can be good for x-ray or neutron diffraction studies. If you want to ...


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The presence of a ductile to brittle transition temperature implies there are insufficient (ductile) deformation modes at low temperatures to support plastic deformation and therefore fracture occurs to release energy/load. In FCC materials, dislocation slip of both edge and screw dislocations is relatively athermal and due to the number of active slip ...


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One would expect that a positively charged sphere could hold a different amount of charge than a negatively charged one, one reason being that the tunneling probability for electrons to escape would tend to be different than for ions. There may be other effects as well that could cause a difference. If I were to venture a guess I would suppose that more ...


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Take a piece of string (I just use cheap yard twine) and soak it im rubbing alcohol. Then wrap the soaked string around the glass tube along/in the score mark you made. Then light the alcohol soaked string on fire. let it burn for a few seconds then dip the gloss tube in cold water and it will break along you score line.. I personally use this method in ...



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