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Comment to @SK Dash - quantum fluctuations are not thermal bath (how do they distribute and couple to various degrees of freedom?), so the associated energy scale can hardly be called temperature.
The equation you wrote is more of a definition for heat capacity C ($Q = \Delta E = \frac{\partial E}{\partial T} \Delta T$), unrelated to "vacuum temperature&...
3
The ideal gas law takes no account of weather patterns over land and water; it takes no account of atmospheric circulation. So the connection you attempt to draw between the gas law and weather reporting is invalid.
Furthermore, the gas law's relationship between temperature and pressure you cite requires that the volume be held constant. No such rule ...
3
What makes atoms move faster if they get external heat energy?
Heat is energy transfer due to temperature difference. Temperature is a measure of the microscopic average translational kinetic energy of the atoms and molecules.
Fundamentally, atoms and molecules move faster as a result of heat transfer because microscopic kinetic energy has been transferred ...
3
In thermodynamics atoms are treated as point-like objects, whose only energy is the kinetic energy:
$$K = \frac{mv^2}{2},$$
i.e. having higher velocity (being faster) literally mean shaving higher energy and vice versa.
How atoms increase their energy depends on how the heat is transferred to the system. For example, if one mixes two gases at different ...
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Is there a quantitative description of this process somewhere
that will tell me what the equilibrium temp will be?
The Stefan-Boltzmann law says how much radiation
an ideal black body will emit:
$$j_{\text{emitted}}=\sigma T^4 \tag{1}$$
where
$j_{\text{emitted}}$ is the total emitted power per area,
$\sigma = 5.67\cdot 10^{-8} \frac{\text{W}}{\text{m}^2\...
2
Rest being constant, the rate of effusion is inversely proportional to the square root of the absolute temperature.
But why is it so?
I mean as the absolute temperature increases so does the average kinetic energy of the molecules. So shouldn't the rate of effusion increase?
The reason is, if pressure difference stayed the same, density difference had to ...
2
This is for @Alecksy Druggist
Suppose that the objects are perfect cubes of side S. We will focus on the left cube which is the hot one, and which is insulated on its left side, x = 0, and is in contact with the cold cube on its right side x = S at constant temperature $T_S$. The transient temperature variation within the cube is described by the transient ...
1
As far as I can tell temperature seems to be defined as something like
average kinetic energy per molecule
No. A glass of water with some ice cubes, in approximately thermal equilibrium in a refrigerator, has a temperature of $O^{\circ}C$. Both the ice and the liquid water have that temperature. But the average thermal energy of the molecules of liquid ...
1
In the chapter calorimetry of class 10 I read that heat energy is the
total energy content of a body, that is sum of the kinetic energy of
the molecules and their potential energy due to the attractive forces
between them.
That is totally wrong. The total energy content of a body is its internal energy, that is, the sum of its kinetic and potential energies ...
1
(a) What's being defined in your first paragraph is internal energy, not heat.
[Heat is energy in transit spontaneously from a region of high temperature to a region of low temperature.]
(b) Vigorously vibrating molecules transfer energy to our skin making its molecules vibrate more vigorously. Some of our nerve-endings transfer this information as an ...
1
Entropy is not actually the measure of number of states. Imagine a dice that only rolls numbers $1$ and $2$. It has $6$ faces, sure, but the other $4$ are impossible. How is this dice any different from a coin? What if the probability of the other $4$ faces are nonzero, but are very small (lets say, $0.00001$%), wouldn't the entropy still be very similar to ...
1
Keep in mind that entropy is the logarithm of the number of states. Going from one possible state to ten results in the same increase in entropy as going from ten to a hundred. Assume, totally incorrectly, but just to illustrate the point, that increasing energy by a fixed amount results in a fixed amount of possible states being added. Then entropy would ...
1
It is due to the pressure difference between inside the can and outside.
When you blow up a balloon you are pushing more air particles inside it than would like to be there. As soon as you pop it they all rush out. This is because they are getting pushed more from behind (from the many more air particles inside the balloon) than from the outside (the ...
1
You are determining the combination of both. If the two bodies are identical, then, at the contact surface between them, the temperature will be the arithmetic average of the original temperatures throughout the equilibration. In this case, it is easy to resolve the separate contributions of generation and transfer, because the entropy transfer is just ...
1
The mechanism of heat transfer depends on whether the transfer is via conduction, convection or radiation and whether it takes place internally in a solid, a liquid, a gas, or at the interface between two different substances.
Broadly speaking, heat transfer can be by emission and absorption of electromagnetic radiation; by transfer of vibrational energy ...
1
The problem with the argument comes in the line "However, pressure in a fluid is caused by nothing other than the collision of water molecules against other things." Pressure in an ideal gas is caused by nothing other than the collision of gas molecules. Pressure in condensed matter comes from interatomic repulsion.
It's true that when you ...
1
When the objects are exposed to sunlight, they are heated by radiation, and cooled mainly by convection: $\frac{q}{A} = h(T_{obj} - T_{air})$, where $h$ is the convective coefficient.
The black surface absorbs more heat by radiation than the white one. So, the $1000 W/m^2$ is close to the reality for it ($\epsilon \approx 1)$, where $\epsilon$ is the ...
1
For surfaces surrounded by air and exposed to sunlight or other e-m radiation, the main reason for black ones getting hotter is that they absorb radiation but lose heat mainly by convection, which process is much less dependent on surface colour. Thus a body with a matte black surface has to get hotter than one with a shiny surface in order to lose heat at ...
1
Pressure can be thought of as the average force per unit area caused by molecules hitting the walls of the chamber, or the average rate of change of momentum of molecules hitting the walls. The molecules of warm air have a higher average kinetic energy. Higher kinetic energy means higher average speed. Higher average speed means higher average momentum. ...
1
If the Dewar flask is an ideal insulator then in Scenario 1, no ice will melt at all.
But in Scenario 2, adding some water to the ice will make some of it melt (the more water added, the more ice will melt)
So for a perfect insulating Dewar flask, Scenario 1 will ALWAYS leave the most ice. It's trivial, really...
But if the Dewar isn't perfect, the ...
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