# Tag Info

### Why is the $ΔT$ for the heat transfer of the copper segment, like in the picture, $(100 - T)$ instead of $(T - 100)$?

The equation being applied is Fourier's law. $\Delta T$ doesn't represent a temporal change (where we might apply a convention of $T_\mathrm{final}-T_\mathrm{initial}$) but a spatial change. ...
1 vote

### A bit funny practical task: frozen dumplings in boiled water, how temperature changes and when will boil again?

Assuming you have boiling water and standard conditions (T = 20°C, P = 101.3 kPa) and do not add any energy to it, it will stop boiling due to heat loss to the environment. There is no need to add the ...

### Resistivity: related to $V/I$ or $dV/dI$?

In principle, we distinguish static and differential resistivity. The differential resistivity depends from the point on the current-voltage characteristics where we calculate the derivative, so we ...
Accepted

### Why Curie temperature is bigger for smaller lattice in 2D Ising model

Why numerical simulation gives seemingly wrong result? The exact expression for $T_c$ is given by $$T_c=\frac{2J}{\ln\left(\sqrt{2}+1\right)}\approx 2.269\,J,$$ where we assume that $k_B=1$. This ...

### Calculating temperature when it is lower than your thermometers can read?

Take some liquid, put 10% of it in the freezer, wait a few hours. Measure the temperature of the liquid you left out, then pour in the liquid from the freezer, and measure again. The temperature of ...
1 vote

### Calculating temperature when it is lower than your thermometers can read?

Adding a known amount of energy via a microwave oven Pour a known volume/mass of water into a lightweight plastic cup. Let's assume you pour 100 ml = 100 g. Place the cup into the freezer and allow it ...
1 vote

### Thermodynamics and Special Relativity

What happens to the temperature of a body (not in the body frame) as it approaches the speed of light? As discussed in this article, no one can tell you the answer, at least unless you choose a ...

### Frost on my windshield at 40° f on a clear cold still morning?

Yes, different kinds of heating/cooling (heat transfer) have different "strengths". Contact heating/cooling is when you touch a warm/cold object and heat flows from the warm to the cold side....

### Calculating temperature when it is lower than your thermometers can read?

The freezing point of water ethylene glycol mixtures depends in the concentration of ethylene glycol. You can find data for this on the Engineering Toolbox web site (a valuable source of all sorts of ...

### Water Vapour and Liquid Water Interactions

There is absolutely nothing stopping them, and in fact water molecules are constantly hopping between the phases to a degree dictated by the temperature of the system. The proper term used to describe ...

### Temperature of gas particle travelling in space doesn't make sense

Thermal radiation is kinetic energy becoming orbital energy that gets radiated away when electrons revert to their ground state, right? The electron in a hydrogen atom can't lose energy if it's in the ...