Questions tagged [temperature]
It's the physical property that indicates the degree/intensity of heat present in a substance or an object. It can be expressed and measured according to various scales.
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What differs temperature from the mean kinetic energy of a particle?
The mean kinetic energy of a particle for an ideal gas is related to temperature by:
KE = (3/2)kT
My question is why KE $\neq$ T. To me it seems a far simpler ...
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Will hot object near ceiling vent create more draft? [closed]
As in the picture, we have a room with vents at the bottom to let cold air in and at the top to let hot air out. Normally the air flow is limited by the temperature gradient (correct me if I'm wrong). ...
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What does heat do to atoms? [closed]
If infrared energy is absorbed as velocity and not a force, is it the electron spin that is absorbing as seen by frequency? How does it work for increased velocity, could it work to decrease velocity ...
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What is the number density of CMB at higher temperature? [closed]
What was the approximate number density of CMB photons when the CMB had a higher temperature of 897 K? (Hint: You can assume that photons in a thermal distribution have a mean energy of 3kT). Answer ...
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How to calculate habitable zone for Exoplanets? [closed]
I have a question about the habitable zone of stars for exoplanets, which arises from the fact that the "habitable zone" is essentially a myth, as you can tell from Earth, which, without the ...
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What happens to entropy and energy when you inject heat into 2 systems in thermal equilibrium?
Below we have a system A and B in thermal equilibrium. What happens to the entropy and energy of the systems when you inject heat into system A and let it equilibriate further? I know that heat will ...
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Can a propagating sound wave change the temperature of the medium?
When air molecules are given energy they compress the layer of air molecules next to them and so on which causes a high pressure wave to move forward so does this make any change in the average ...
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Would an object moving close to the speed of light appear colder to a stationary observer? [duplicate]
If an object moves close to the speed of light time will slow down in its reference frame as seen by a stationary observer. If my understanding is correct, this means that all movement - such as the ...
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Temperature coefficient for avalanche breakdown
I am having trouble understanding why is temperature coefficient for avalanche breakdown is positive?
The explanation I found online says as the temperature increase the mean free path decreases ...
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Practical application: questioning the value of insulating a car battery [migrated]
Living in the north, I am wondering if a sitting car battery's chemical reactions give off enough heat to justify insulating it. That is, will it result in significantly more power available to start ...
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Weird derivative with respect to inverse temperature identity in Tong's statistical physics lecture notes
While reading David Tong's Statistical Physics lecture notes (https://www.damtp.cam.ac.uk/user/tong/statphys.html) I came across this weird identity in page 26 (at the end of the 1.3.4 free energy ...
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Gibbs Free Energy change under non-constant temperature
The Gibbs Free Energy is defined as $G=H-TS$
Therefore, $\Delta G=\Delta H - T\Delta S - S\Delta T$
When temperature is assumed to be constant, $\Delta G = \Delta H - T\Delta S$, which yields the ...
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Is the global temperature of the earth a physical quantity at all? [migrated]
In discussions with physically educated among the deniers of the greenhouse effect, it is repeatedly claimed that it is completely pointless to state a quantity such as a global average temperature of ...
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Temperature integrations
I'm asking myself a question related to temperature integration. First is possible to integrate a temperature distribution over the time and over a certain volume?
If yes, these resulting integrals ...
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Determine the temperature of the Earth without an atmosphere using thermal inertia rather than Stefan-Boltzmann
I’m asking the question because I have no idea how to do the math.
The recent data from NASA’s LRO mission and the readings from the Chandrayaan-3 landing site would seem to provide enough data to use ...
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Why are temperature and specific volume independent properties in thermodynamics?
If we have a sealed piston-cylinder with gas inside and we heat it from the outside, the temperature changes. At the same time, if we look at it as a control mass system,the volume increases as the ...
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Can something become hot enough that it stops glowing?
So I understand that matter emits EM waves when hot. And that the higher the temperature, the shorter the wavelength, so cooler flames start off orange and the hotter flames reach light blue and white....
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Solving the heat equation around a point of constant temperature
I have a heterogeneous medium, of temperature $T=0$. Inside this medium (let's say, at the origin) is a small (let's say infinitesimal) source of thermal energy, which is kept at a constant ...
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How do you know mercury changes monotonically with temperature if mercury itself is used to make the thermometer?
In the book I am reading recently "Concept of physics" volume 2 by professor H.C. Verma it says that (I am just summarizing the main points chronologically)
Energy is transferred from hot ...
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Thermal equilibrium, heat and temperature [duplicate]
I am just studying thermodynamics for the first time and confused between these three terms
Temperature is defined in terms of thermal equilibrium (from zeroth law of thermodynamics) and thermal ...
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Would there be a flame front in an air-fuel mixture? [closed]
Suppose a piston enclosing an amount of air-fuel mixture and then this piston compresses the mixture to the point of auto ignition, if every part of the mixture ignite simultaneously is it safe to say ...
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Using $S$ and $T$ to parameterize thermodynamic state
During an exercise session in school we worked on Problem 1.4 in Equilibrium Statistical Physics by Plischke and Bergersen. This chapter is a repetition of thermodynamics, and the problem concerns a ...
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Is there an upper limit to temperature in the universe?
The Sun's core temperature has been modelled to be $\approx 1.57 \times 10^7$ K
In supernovae:
"In lower mass cores the collapse is stopped and the newly formed neutron core has an initial ...
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Hagedorn Temperature of Type I Superstring
In many sources, the Hagedorn temperature of different string theories is given using the high temperature (or high-level limit) $N\gg1$ in the calculation of the string entropy such that:
$$T_H=\left(...
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Can the Antoine equation be used without making vacuum?
The Antoine equation is a semiempirical formula, derived from the Clausisus-Clapeyron relation, which allows the vapor pressure $P$ of a pure substance to be approximated by
$$ \log_{10}(P) = A - \...
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How does athmospheric pressure influence dewpoint?
I have a sensor that measures temperature, relative humidity and air pressure.
All the formulas I could find for both absolute humidity and the dew-point only use the temperature and humidity values, ...
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Temperature sensor in decimal accuracy in room temperature?
I am designing a device, in one of its parts there i need to collect any ticker of room temperature data for its local purpose of device in decimals counter recording such as 30 digits after 21 degree:...
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Measurement that takes into account air density and average kinetic energy?
I think in very thin air, high average kinetic energy of air molecules might still be perceived as cold because the number of impacts per unit time would be fewer. Is this a measure that combines ...
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Is kilo-Kelvin ($\rm kK$) avoided as it would be confusing?
When describing the colour of light globes, you see temperatures like 2700 K or 6000 K.
The surface of the sun is around 5500 K.
This could be written as 2.7 kilo-Kelvin or 2.7 kK (or 6 kK, 5.5 kK ...
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Total temperature when combining two systems of unequal temperature [closed]
I know that intensive properties a characterised by the fact that when you combine two systems (A and B) that have the same value of an intensive property (for example same Temperature) the combined ...
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Interpretation of Temperature
In differential form, the First Law of thermodynamics can be phrased as
$$ dU = T\,dS - P\,dV + \sum_{j = 1}^N \mu_j\, dn_j, \quad (1)$$
or equivalently as
$$ dU = \left( \frac{\partial U}{\partial S}\...
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Is an Isothermal Process really possible? Heat cannot convert into work with 100% efficiency!
We know that heat is an energy of higher entropy (Diffused/Dispersed Energy). Work is the energy of lower entropy (Concentrated form of Energy). We know that entropy cannot reduce on its own, but we ...
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*Why* does global warming lead to more extreme weather events? [closed]
I read several times about global warming leading to more exteme weather events, i.e. flooding, droughts and even winter storms occuring at higher rates and with more intensity.
So, higher temperature ...
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Book recommendations on climate science
I've had my eye on properly understanding climate, climate change and the wide array of phenomena related. But, as a physics grad student, I'd fancy more exact, math-based bibliography, that treats ...
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Why does solubility of $\rm NaCl$ increases with increase in temperature? [closed]
If the volume of water decreases with increase in temperature then why does solubility of $\rm NaCl$ increases with increase in temperature…i mean to say that if the volume increases then the ...
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Why does the boiling water in the pot get sucked up by the jar?
In order for the jars to be sterilized for pickling tomatoes, they need to be boiled. But when one of the inverted jars was standing on the rack in the pot, it started sucking in the water that was ...
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Can a broken chemical bond be made again?
My question is that if we raise the temperature of a substance carrying chemical bond …….then will the bond be made again by itself by cooling down the temperature?
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What are the hex color code equivalents for the different classifications of stars?
Stars appear to be of various colors based on the visible light they emit. I am wondering if there is a hex color code that can be considered to be typified or average for the various classifications ...
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From where does the particle in liquid get energy to move always?
My question is that if there is an object,then without giving energy to an object it cannot move …so my question is that how do particles in fluids always move without giving them any additional ...
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Estimate the Sun's temperature, based on the duration of sunrise
The full problem statement is:
Measured from the time when the first rays of sunshine appear above the horizon until
the moment when the sun is fully visible, sunrise lasts 2.1 minutes. Based on this
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Why thermodynamic arrow of time will not reverse during the big crunch (considering our universe is above the critical mass)?
As the question states, Why thermodynamic arrow of time will not reverse during the big crunch (considering our universe is above the critical mass)?
The doubt arised because I thought the ...
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Same temperature implies thermal equilibrium
A particularly weak formulation of thermodynamics is
Two bodies are said to be in thermal equilibrium if no heat transfer occurs when they are put in diathermal contact. Thermal equilibrium is an ...
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What technological advance would a room temperature superconductor allow? [closed]
I have read a recently published paper on arXiv where the scientists claim to have developed a superconductor material working at room temperature and pressure.
While it is clear that the results - if ...
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Understanding how the Nernst statement of the Third Law implies the Planck statement
I am reading Callen who, up to and including where I am at (Chapter 11), treats thermodynamics as a classical theory with only the maximum entropy postulate for isolated systems sprinkled in as a &...
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Fourier Transform of temperature Green Function
I am doing a calculation involving a temperature Green function for some operator $\hat{A}$:
$$G_{\hat{A}}(\tau)=-\Big\langle{T_\tau\big(\hat{A}(\tau)\hat{A}^\dagger \big)} \Big\rangle=-\theta(\tau)&...
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Forced convection and active temperature?
I performed anisothermal CFD computations with large eddy simulation.
Is the use of the temperature as an active scalar relevant when performing a forced convection RANS or LES computation (Ri<0....
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Where does heat go at an atomic level in all phases of matter? [closed]
I'm trying to understand where heat energy goes in a substance. I've seen that mainly it's translation at lower temperatures, rotation at mid range, and vibration at high range, but I'm not sure of ...
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How high pressure, high temperature liquid refrigerant exiting a Thermostatic Expansion Valve (TXV) turns into low pressure, low temperature liquid?
In a refrigerator or heat pump, how does high pressure, high temperature liquid refrigerant exiting a Thermostatic Expansion Valve (TXV) turn into low pressure, low temperature liquid? Is this a ...
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Effect of Sun temperature on the thermosphere
Correct me if I’m wrong here.
The thermosphere is hot due to its absorption of moderately high energy UV radiation. (<200nm)
Cooler stars emit fewer high energy photons. So if the Earth orbited an ...
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A question about colour temperature
This picture from Wikipedia is a table of temperatures vs colour for incandescence, however the problem is that I’ve been told that for a black body, even something with a temperature of say 2000C (E....
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