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Temperature vs time plots, showing the Mpemba Effect. The Mpemba effect is the observation that a liquid (typically water) that is initially hot can freeze faster than the same liquid which begins cold, under otherwise similar conditions. There is disagreement about its theoretical basis and the parameters required to produce the effect. [1] [2]
In this scenario, the transition temperature is known as the calorimetric ideal glass transition temperature T 0c. In this view, the glass transition is not merely a kinetic effect, i.e. merely the result of fast cooling of a melt, but there is an underlying thermodynamic basis for glass formation. The glass transition temperature:
Vitrification (from Latin vitrum ' glass ', via French vitrifier) is the full or partial transformation of a substance into a glass, [1] that is to say, a non-crystalline or amorphous solid. Glasses differ from liquids structurally and glasses possess a higher degree of connectivity with the same Hausdorff dimensionality of bonds as crystals ...
Thus, indirectly, thermal velocity is a measure of temperature. Technically speaking, it is a measure of the width of the peak in the Maxwell–Boltzmann particle velocity distribution . Note that in the strictest sense thermal velocity is not a velocity , since velocity usually describes a vector rather than simply a scalar speed .
Liquidus temperature curve in the binary glass system SiO 2-Li 2 O. For impure substances, e.g. alloys, honey, soft drink, ice cream, etc. the melting point broadens into a melting interval. If the temperature is within the melting interval, one may see "slurries" at equilibrium, i.e. the slurry will neither fully solidify nor melt.
This happens if the cooling rate is faster than a critical cooling rate, and is attributed to the molecular motions becoming so slow that the molecules cannot rearrange into the crystal positions. [21] This slowing down happens below a glass-formation temperature T g, which may depend on the applied pressure.
Values of the Biot number smaller than 0.1 imply that the heat conduction inside the body is much faster than the heat convection away from its surface, and temperature gradients are negligible inside of it. This can indicate the applicability (or inapplicability) of certain methods of solving transient heat transfer problems.
where m is the atomic mass, ν is the frequency, u is the average vibration amplitude, k B is the Boltzmann constant, and T is the absolute temperature. If the threshold value of u 2 is c 2 a 2 where c is the Lindemann constant and a is the atomic spacing, then the melting point is estimated as