42
Technically, it all is the same motion. The difference is magnitude and direction and how you separate out the superposition of them.
Temperature is a result of the components of motion (vectors) of each individual air molecule with a net translational movement of zero over time. This motion is random and all over the place in many directions as they move ...
16
Temperature is related to motion, yes. And wind is motion. But numbers matter.
A particle with temperature $T$ (in absolute units, like Kelvin) will typically have a kinetic energy of approximately $kT$, where $k$ is Boltzmann’s constant. For nitrogen and oxygen molecules at room temperature, the typical speed associated with this typical kinetic energy is a ...
8
There seem to be at least two valid ways in which physicists and engineers use the term Ohm's law, neither of which is merely a definition of resistance.
(a) If $I$ is proportional to $V$ then the conductor obeys Ohm's law, otherwise it doesn't.
(b) At constant temperature (and, strictly, at constant pressure) metallic conductors and most single-substance ...
6
Using the Debye model leads to the Lindemann melting formula for the melting Temperature: see reference), for p = 1 bar there is an upper limit for a given material structure.
$T_m = \frac{4\pi^2 A\, r_0^2 k_B \eta^2 }{9N_Ah^2}\Theta_D^2\,$ in K with A atomic mass, $r_0$ interatomic distance, $\eta$ Lindemann factor = 0,2 - 0,25 and Debye temperature $\...
6
You have correctly deduced that the rate of heat transfer to the system is negative. This means that heat is leaving the system (that is leaving the filament).
What is heat? Heat is energy in transit from a higher temperature region to a lower temperature region due to the temperature difference.
In this case the filament is very hot and the surroundings are ...
5
There are already two amazing answers above, but I think explaining it more simply might be helpful:
Molecules in wind have vibrational motion as well as translational motion.
The vibrational speed is higher than the translational speed(in general situations).
The more the vibrational speed, more is the kinetic energy in the molecules, hence more the heat ...
4
Wouldn't the rate of heating be zero?
As @Chemomechanics very succinctly stated:
$Q$ is negative. $Q$ is the heating of the system, not by the system.
The 1st LoT may not be the most interesting description of what is going on in the filament, in terms of internal temperature profile e.g.
In this answer of mine (scroll down to below the break) I applied ...
4
no, it can't. the gas molecules in a mixture are continuously undergoing collisions with every gas molecule in the mixture, and thereby sharing their kinetic energy in every possible way. If you could heat only one gas in a mixture, it would share that energy with all the other molecules so quickly that the gases would have no time at all to segregate ...
3
The Unruh temperature depends on the magnitude of the acceleration, which is a scalar.
3
The recovering ex-engineer weighs in.
Note that for most common engineering metals, the temperature coefficient of resistance is small. This means that for temperatures not far from ambient, the shift in resistance caused by ohmic heating is small enough to ignore, and so engineers (even recovering ex-engineers) will indeed ignore it.
This means that ...
2
One can definitely do thermodynamics and statistical mechanics on systems of orbiting point masses. See Galactic Dynamics by James Binney and Scott Tremaine for a through treatment. Basically, one can calculate the evolution of the probability distribution of velocities at different points over time.
The problem is that the system is not in thermal ...
2
Actually, the final temperature is 49 C. If C is the heat capacity of the liquid water and $T_R$ is taken an absolute reference temperature for zero entropy for water, then the initial entropy of the 1 kg of water is $(1)(C)\ln{[(273+7)/T_R]}$, the initial entropy of the 2 kg of water is $(2)(C)\ln{[(273+70)/T_R]}$, and the final entropy of the 3 kg mixture ...
2
wouldn't it make more sense to for these bond strengths to be continuously increasing instead of only increase at 2 distinct points
There's a misconception here: the bond strengths don't increase at those points, that's when they form at all.
It's probably easier to think of it like that: the molecules, as they lose energy (i.e., as the system cools down), ...
2
"Investigation of gas separation technique based
on selective rotational excitation of different
species by a laser", Phys. Fluids 32, 087106 (2020)
Abstract
"In this work, a gas separation approach based on the selective rotational excitation of different species is investigated. The presented method is particularly suitable for separating ...
1
Start by considering the vapour in equilibrium with the liquid. For the two to be in equilibrium they must have the same molar Gibbs free energy. As a rough approximation the Gibbs free energy of the gas depends most strongly on its pressure while the Gibbs free energy of a liquid depends most strongly on its temperature. So for the two to stay the same the ...
1
A monoatomic ideal gas has mean energy $\frac 32 kT$ per particle, or a molar heat capacity of $\frac 32 R$, where $R$ is the ideal gas constant. A mole of completely ionized helium will have mass four grams and heat capacity $3\times\frac32 R$, because each free nucleus is accompanied by two free electrons.
You would be amused by this answer, which ...
1
To a first approximation the palm shows a blackbody radiation spectrum of a 37C surface, which would be a smooth continuous function. It peaks around 10 micrometers.
However, there are deviations from this curve due to different emissivity at different wavelengths. If the emissivity is low (it is more reflective and releases less radiation on its own) the ...
1
The outer part of a neutron star is considered solid and its temperature can reach $10^6$ K. This is probably the highest temperature that a solid can reach.
1
Frozen water is less dense than the liquid water, so when icicles are formed, they are moving up, so the ice always builds up at the top of a body of water. If the water reservoir is deep, then, because of thermal capacity of a large volume of water it does not get frozen completely from top to bottom.
The ocean water does not get frozen to the bottom ...
1
The graphs below shows three conventional ways of graphically presenting Boyle's law. As observed from the graphs below, the pressure increases with a decrease in volume, and vice versa. Pressure is inversely proportional to volume, so other parameters (temperature and amount of gas) are constant.
Charles's law states that the volume of a gas increases with ...
1
Vacuum does not contain radiation nor other electromagnetic fields.
Stationary and constant velocity vacuums do not have any temperature. Accelerated vacuum has a temperature - the Unruh temperature:
$${\displaystyle T={\frac {\hbar a}{2\pi ck_{\mathrm {B} }}}}$$
It is very weak. In the acceleration of Earth's gravity it is only $4×10^{−20}$ K.
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