# 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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### Deriving Planck's Constant from Wien's Displacement Law

So I'm reading an introductory book on Quantum Theory (David Park, 3rd ed.) and I am having trouble with the following question: "According to Wien's displacement law, the wavelength $\lambda_m$ at ...
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### Temperature of vacuum chamber on Earth

Does the temperature of a vacuum chamber drop if left for 24 hours or more, since some in space in quite cold somewhere and quite hot how does vacuum become cold near to absolute zero.
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### Swap protocol in parallel tempering MCMC simulations

Consider a parallel-tempering Markov-Chain Monte Carlo (MCMC) simulation of a system, with inverse temperatures $\beta_1 < \cdots < \beta_N$ and energies $E_1, \cdots, E_N$. If there are two ...
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### Ferromagnet $\leftrightarrow$ paramagnet at Curie temperature

I think it's like this: $\, m=\tanh\left(\frac{Bμ}{k_bT}\right)$. If now the temperature decreases, then $\mu$ increases, until it flattens out ($\tanh$ function). Is the a point where $m$ flats out, ...
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### Negative Temperature Without Statistical Mechanics

In plenty of the qualitative thermodynamics that predates the statistical description, temperature is assumed to always be positive; many key inequalities related to the second law often involve ...
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### How does sound melt concrete?

The sound power level (SPL) of the Saturn V rocket engines were 220 db. There are numerous websites that state this is loud enough to melt concrete. An example from the website makeitlouder.com 220 (...
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### How would a particle behave when its wavelength is lesser than a planck length

If we increase the temprature of a body so much that its wavelength becomes lesser than the plank length, the quantum nature could breakdown as the wavelength of the particle is lesser than the so ...
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### Can Entropy Change be negative in this situation?

The temperature of two moles of an ideal diatomic gas is decreased from 𝟔𝟎𝟎 𝐊 to 𝟑𝟎𝟎 𝐊 at constant pressure. Is entropy change negative?
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### Would setting the ideal gas constant to $1$ yield an attractive natural temperature scale? [closed]

In this recent question, there was a comment 'The "zero point" of Kelvin is natural, but the scale is not'. This led me to wonder whether setting $R = 1$ in the ideal gas law would be an attractive ...
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### Formula of viscosity

viscosity formula = η = F̅/A(shear stress)=Δvx/Δz but i noticed that viscosity depends upon temperature too.Shouldnt there be temperature variable too in the formula ?
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### Why is the length of the Kelvin unit of temperature equal to that of the Celsius unit? [duplicate]

The Celsius unit is arbitrarily defined, based on the boiling and freezing point of water. Is it a coincidence, then, that the SI unit of temperature Kelvin, which is used in all natural equations, ...
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### Are there gases that cool down as energy is added?

If there are, please provide examples. Lee Smolin suggests there are such gases in his book, "Time Reborn", but searching on my own, I could not find examples, and it seems hard to accept this is ...
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### The significance of kelvin as a unit of absolute temperature

$$PV=nRT$$ Where $P$ is pressure in pascals ($\text{Pa}$) $V$ is volume in cubic metres ($\text{m}^3$) $n$ is amount of substance in moles ($\text{mol}$) $R$ is the gas constant having units, joules ...
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### What is the physical explanation for Newton's laws of cooling?

In my calc 1 class we covered these laws and (rate of change proportional to difference in temperature) I would like to know why they are true, or at least why they work as close approximations. Is it ...
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### High velocity mushrooms?

So y’all know meteoroites burn up in our atmosphere I’m looking for an equation or something that will allow me to calculate how fast a substance can move before it starts to burn up. Specifically I’m ...
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### Why is pizza soggy after microwaving?

Compared to when heated over fire, pizza is soggy when heated in a microwave oven. I want to know why this is. So far I’ve just learnt that microwaves in ovens are of a specific frequency of ...
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### Is the sun required for evaporation?

I understand that the sun would heat up a pool of water causing the overall temperature to increase. This would also mean that more molecules would have enough energy to escape the pool, but wouldn't ...
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### Is constant temperature and thermal equilibrium same thing?

Can you give some examples which would reveal whether they are same things or not?
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### Why do the tyres of the vehicles burst during summer?

The explanation of most is -According to Charles' law if the temperature increases volume should also increase and hence the tires burst. But it is also that if volume increases pressure decreases (...
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### How can internal energy be expressed as a function of any two of $p, v, T$?

In the book of Irey, Theormodynamics, the author states that (while talking about single phase substances) For a simple compressible media, we may choose our measurable independent variables any ...
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### Are birds warming up on high voltage lines?

Birds are unharmed on high voltage lines, because they touch only one wire and don't experience voltage as the difference of potentials. However, birds also seem quite comfortable there. Could this be,...
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### The physics of the startup of a lava lamp

I noticed a strange phenomenon observing a lava lamp. We all know the complex flow of bubbles when the lamp is "hot" and running, but I would like to have some explanation about the startup behavior ...
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### Can Hydraulic System work on a Moon Robot?

Since the Moon has no atmosphere and the temperatures reach maximum 123 C and min minus 153 C, how feasible is it to use hydraulic actuators to move the Robot legs? Since my assistant Professor ...
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### System of particles in classical mechanics and classical statistical mechanics

$\bullet$ Both classical mechanics and classical statistical mechanics can describe the properties of a system of classical particles. $\bullet$ In classical statistical mechanics, we assume that we ...
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### Predicting the effect of a power outage on the temperature in my fridge

I have a commercial fridge, without a freezer. It is vertical fridge with one glass door. We have medications we want to keep below 8°C. Most medication tolerate a slight T elevation without problem. ...
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### Conversion of $R = 8317\ \mathrm{\frac{J}{kg\cdot mol\cdot K}}$ to $8317\ \mathrm{\frac{J}{kg\cdot mol\cdot {^\circ C}}}$

I'm trying to understand the unit conversions when one unit is obtained by shifting the value of another one by some constant. In particular, the unit conversions from Kelvin to Celsius scale: T(\...
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### How does an ultrasonic humidifier / atomizer affect temperature?

Evaporative cooling is a technique used to cool air by using the evaporation of a liquid. My google research on evaporative cooling shows a ubiquitous concept of forcing air through a pad/membrane/...
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### Why does diamond's specific heat capacity deviate from the Dulong-Petit theory at room temperatures? [closed]

Why does diamond deviate from the prediction of $c_v = 3k_B$ at room temperature more than other solids. Why do we require Debye's theory instead?
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### Thermodynamics, Phase change diagrammes

What would be the phenomena and PV, TV diagrammes for a closed vessel partially filled with water and subjected to heat, How change in vapour pressure would effect its boiling?, How PV, TV diagrammes ...
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### Apparent temperature of the universe at relative speeds

Suppose you are in a vessel traveling at relativistic or near relativistic speed relative to your local galaxy--whatever is physically reasonable, and won't get rapidly torn apart by high energy ...
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### Which is positive? which is negative? about laws thermodynamics…from problem solve

1) A hot block of iron does 50 kJ of work on a cold floor. The block of iron also transfers 20 kJ of heat energy to the air. Calculate the change in energy (in kJ) of the iron block. 2) A chef ...
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### Why do electrons revolve around the nucleus? [duplicate]

Why do electrons revolve around the atom's nucleus? Where does it get the energy for the revolution? Do the electrons stop revolving at absolute zero temperatures?
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### How big of a temperature difference is needed to power a thermoelectric generator?

I'm really curious about this and haven't been able to find a formula to calculate the types of voltages I could generate based on differences in temperature. An example of interest is The PowerPot ...
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### Semiconductor and temperature dependence

Does the conductivity of both intrinsic and extrinsic semiconductor increases with temperature or is it that conductivity of extrinsic semiconductor decreases with temperature just like a conductor ?
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### How much energy from air to ice? [closed]

If... "A" is the mass of air (standard air composition and pressure) "I" is the mass of ice "V" is the volume of the box where the change of heat happens (no heat interaction with out of the box) ...
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### Blowing smoke out of the clean air - can someone explain?

Yesterday my wife and I were out walking. The weather was cloudy and humid (it had been raining a few hours before). Around 15 C. Suddenly, with no apparent reason, both of us had smoke coming out ...
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### When the external resistor increases in temperature, why is the calculated value for internal resistance higher?

Say we had a circuit with a cell (with internal resistance)and an external resistor of 10 ohms as shown: The 10 ohm resistor then increases in temperature, leading to an increase in resistance in ...
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### If a steam injector increases pressure by lowering temperature would a 'refrigerant injector' work using ambient heat?

In a Giffard type steam injector, boiler feed water is added to the boiler by passing steam at around 10 bar/180C through a converging/diverging nozzle, collecting cold water in the vacuum at the vena ...
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### How to calculate the actual pressure in chamber with reduced pressure but at increased temperature?

I would like to find out the actual pressure in a chamber (constant volume) where the pressure within is reduced to 1.5 kPa but with increased temperature to 65˚C. How to calculate this? Assuming 0....
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### How bright was the universe after Big Bang during photon epoch?

After 10 seconds of Big Bang, most of the leptons and antileptons annihilate each other leading to an outburst of photons. The universe was said to be dominated by photons resembling a glowing fog. ...
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### What is the temperature at which Napalm burns?

I was sitting during a lecture last week in one of my classes, and we were talking about chemical warfare and the history behind it. My teacher had brought up the use of Napalm during Vietnam. After a ...
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### Why does temperature of a system not change during a phase change of the system if even the internal energy of the system increases?

I can't understand why the temperature of a system doesn't change during a phase change of the system if even the internal energy of the system increases. The problem is that I have never really ...
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### What will happen if my room is half filled with dry ice? [closed]

Suppose we have a sealed room, the room is a cube, half the room is filled with dry ice. What will happen when the dry ice sublimates to CO2, will the pressure of the room increase dangerously as the ...
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### Heat transfer reservoir and system at same temperature

I just read that "a heat transfer between a reservoir and a system at same temperature is a reversible process". If there's no temperature difference, why would there be a heat flow?
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### Would a helium ballon pop or freeze in space?

I have read these questions: Why doesn't Helium freeze at 0K? Do objects in space freeze immediately? Now I do understand that a helium balloon cannot float up to space. But let's assume this ...