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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Temperature at which an object emits electromagnetic radiation

I am learning about blackbody radiation. I am confused about two different statements from two different sources: Source 1 says that "All atoms/molecules above room temperature are accelerating ...
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Why is a throttling valve isenthalpic whilst a nozzle is not?

From my understanding, Nozzle's and throttling valve are devices which both trade pressure for velocity, so they increase velocity at the expense of having to decrease the pressure. If we examine ...
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What is The Cause of Outgassing in Space?

What is the main cause of outgassing in space? Does it only happen because of temperature, vacuum, or both? Is it possible to test outgassing in vacuum chamber or does it have to be a thermal vacuum ...
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Do temperature and pressure affect alumina properties?

Alumina is a ceramic, an electrical insulator, but has a relatively high thermal conductivity with a high melting point. So can all those properties change under pressure and temperature (low or high)?...
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How do mercury tubes keep the period of a pendulum clock constant with temperature?

According to my Halliday-Resnick, the period of a pendulum clock can be kept constant with temperature by attaching vertical tubes of mercury to the bottom of the pendulum. How does this work? My ...
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Measuring temperature at submicron resolution

Do we have any microscopic technique/protocol to measure temperature at sub-micron resolution?
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Unusual temperature shape in gravel heat storage

I’m currently doing undergrad research on using a gravel (basalt 2-5mm grain size) bed as an heat storage. In order to heat up the gravel inside, hot (~100°C) and dry (RF<4%) air with a pressure of ...
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Why the total temperature remains constant through shock wave? [closed]

We know that total temperature is sum of static and dynamic temperature. If static temperature increases through the shock wave, then how total temperature remains constant? It must increase and not ...
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Is there any alloy that has the same oxidation resistance at high temperature?

Iridium is a rare and expensive metal, for those reasons and others I was wondering if there an alternative to it.
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Is my geometric interpretation of $T \left(\frac{\partial S}{\partial T}\right)_P = \left(\frac{\delta Q}{dT}\right)_P$ correct?

I originally started writing this as just a question, but in the process of writing it I may have solved it myself. Still, I would very much appreciate if someone more knowledgeable than myself took a ...
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Isothermal process and first Law

In an isothermal process, $dQ=0$, the temperature remains constant, but if the system does work, then $\text{d}U=-dW$, but if the internal energy reduces due to work done, doesn't that reduce the ...
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Why does the melting point of water decreases with increase in pressure? [duplicate]

My book mentions that the melting point of water, unlike other substances, decreases with increase in temperature. But the book doesn't mentions any reason why it happens as such.I searched on the ...
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Why does water contract on melting whereas gold, lead, etc. expand on melting?

My book mentions that water contracts on melting, but the book doesn't give any reason why it does so. It is mentioned that: $1\,\mathrm g$ of ice of volume $1.091\,\mathrm{cm}^3$ at $0^\circ\mathrm ...
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Intuitive explanation of insulated boundary condition

Could someone please provide an intuitive explanation of why an insulated end of a rod must have a temperature gradient $\frac{dT}{dx}$ equal to zero? Based on the previous question I asked, it seems ...
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Frozen dew explanation

First, look at this picture: This is frozen dew/rain, it was cold this morning and it might have rained during the night but that's not really relevant I think. Here are my questions: Why is the ...
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At what speed does wind generate warming of an object due to drag, making the object warmer than the ambient temperature?

At what speed does wind generate warming of an object? Say I'm outside at 0°F. How fast does the wind have to be to raise my exposed skin temperature to 40°F? Would that wind speed be so high it would ...
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Can pre-compressed refrigerant or other gas be effectively used for air-conditioning? [closed]

Is it feasible to store a very large quantity of precompressed gas that can later be used for cooling the coils in an air-conditioner? For example, an aerosol can such as a deodorant has a cooling ...
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Why does only linear motion of the molecules contribute to temperature?

In my physics class I studied that it is only the linear motion of the molecules and not the rotation of the molecules that contributes to the temperature. But why is that? I studied that temperature ...
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Speed of sound at a specific air temperature [closed]

What is the speed of sound in air at 140°F?
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Is there any intuitive way to understand why heat is a path function but temperature a state function? [duplicate]

My textbook reads Temperature is the degree of hotness or coldness of a place or a body Why is temperature considered a state function but heat a path function, and how are they different from each ...
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Deriving temperature in Blundell. How to determine the equality $\frac{d\ln(\omega_1)}{dE_1} = \frac{d\ln(\omega_2)}{dE_2}$? [closed]

For two systems with Energies $E_1$, $E_2$ that can only exchange Energy with each other and that have $\omega_i(E_i)$ microstates I derive that: $$\frac {d}{dE_1} (\omega_1(E_1) \omega_2(E_2)) = 0$$ $...
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Reference request: Derivation of the $T^5$ dependence of resistivity from electron-phonon scattering?

The scattering of conduction electrons with phonons gives rise to a resistivity that varies with the temperature as $T^5$. Is there a simple textbook derivation of this? Where can I find this?
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How can an object lose energy but still move at the same speed with constant momentum?

I'm studying collisions, and while doing it, the conservation of momentum seems to strike me in a weird way. If the momentum in a system is constant but energy can still be lost through thermal ...
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Many medicine labels inform the user to store below 86°F [closed]

In our medicine labels, every time we see it warn us to keep the medicine under 86 degree Fahrenheit. Why?
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Which temperature is the irreversible Clausius inequality about? (Hotter or colder system? And initial or final?)

Consider a real-life & physically possible scenario in which heat is exchanged between two closed systems at fixed volume. We know that the Clausius inequality for (noncyclic) strictly ...
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What's the relation between temperature and scale factor for arbitrary EoS $-1 < w \le 1$?

I'm considering standard FLRW cosmology for a simple perfect fluid of pressure $p = w \, \rho$, with $-1 < w \le 1$. In the special case of $w =\frac{1}{3}$ (radiation), the temperature is $T \...
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What puts a limit on lowering $\langle T\rangle$ low avg in heat engines?

I have a simple question which is: We know that the thermal effeciency in heat engines increases when we lower the average temperature at which heat is rejected. But the problem is that there is ...
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Why don't we define temperature as a kind of energy? [duplicate]

Currently, the temperature $T$ is defined in relation to the energy $E$ via Boltzmann's constant $k_B$ like so $$ E \: [\mathrm{J}] = k_B \: [\mathrm{J/K}] \cdot T \: [\mathrm{K}]$$ I'm now proposing ...
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Liquid metal p-trap entry into an underground base on planet Mercury

Imagine we one day establish a colony under the surface of planet Mercury and use integrated thermal acoustics to stabilize the subterranean environment. With a both heat and cold storage available, ...
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Does increased air temperature cause increased maximum height of a jump by a person straight up into the air?

Assuming constant pressure, when the air is hotter, on a hot day, it will have less density and therefore cause a smaller fluid upthrust but also exert less air resistance. So, on a hot day, other ...
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What does the equation $W=RT(\ln V_1/V_2)$ mean?

I understand how this equation is derived but I do not know what it means. I understand $R$ can be taken to be work done by a ideal gas with a unit temperature increment. $T$ is the temperature (as a ...
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Stacking peltiers

I want to build peltier based cloud chamber thus I need to cool a thin plate so Qload would be small. I need help to better understand how stacking of peltiers works to achieve the lowest temperature ...
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Average kinetic energy of a molecule [duplicate]

We know average kinetic energy of a molecule in case of gases depends only on temperature. But does same thing applies to liquids and solids as well. I mean does average kinetic energy of a molecule ...
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How can it be shown that a system's entropy is reduced by cooling it?

I have a question on an issue that already bothers me for a longer time now. In quantum computing, one criterion that should be fulfilled is that an ensemble of qubits can be initialized in a low-...
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Total temperature loss of a gas in a duct

I am wondering how to calculate accurately the loss of total temperature of a moving gas which has exchanging heat through walls and pressure drop. More precisely, let's consider a gas in motion in a ...
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I got stuck in the mountains and it is a very cold winter....Will I survive if I do something like this?

I got stuck in the mountains and it is a very cold winter. Will I survive if I do the action shown on the picture? I start rotating a permanent magnet about an axis near a thick iron plate and wait to ...
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Alternative derivation of NVT partition function

I wanted to use an approach based on the Liouville equation to formulate the partition function of the NVT ensemble from its conservation laws. You can see some more about this approach in https://...
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Cosmic drag and heat

http://www.sci-news.com/astronomy/universe-getting-hotter-09037.html Basically the premise of this article is that the universe is restrained by heat and drag in the ether ("spacetime"). Is ...
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Heating of a closed car

The TV know-it-all’s keep telling us that if the air temperature is 90°F, the interior will reach 109°F in ten minutes. Now, I’m not going to make a stink about a generalization, but I’m just curious ...
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Relative humidity at different temperatures misconception

People in hot arid deserts often look at the weather report and find out the RH is 20%. Then they say it's 20% in a warm tropical country, so we're in just as humid a place as that! Doesn't a RH of 20%...
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What is formula for calculating resistance at different temperatures?

I've read that the formula for determining resistance at different temperatures is :- $$R_\theta=R_0 (1 +\alpha t)$$ But in my book it is also mentioned that it is used for small temperature change. ...
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What made aerogel so insulating?

In many science videos, it is shown that aerogel can insulate an extremely high temperature even though it is very fragile, what properties of aerogel made it so capable of insulating heat?
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What’s the temperature at the Schwarzschild “radius”? [duplicate]

Imagine a foolish astronaut who travels into a Schwarzschild black hole. It’s thought that there’s nothing special about the geometry he encounters at the Schwarzschild “radius” (OK, maybe some ...
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Is helium liquid at 0 K?

I just saw in the dynamic periodic table that He is liquid at $-273.15\ ^\circ \rm C$. Is that true? How is that even possible? Can someone explain?
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Will an egg hard boil faster at higher heat?

The water in a pot of water will boil at $100°\text{C}$ regardless of how much heat is applied to it after it begins to boil. The higher the heat, the faster the water boils off (but at $100°\text{C}$)...
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Lithium Ion Battery Remaining Life Cycle Prediction [closed]

What are the parameters required for remaining useful life predictions? For example, battery temperature and battery capacity values are helpful for remaining useful life cycle prediction. Other than ...
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(How) Does temperature affect the light absorption of molecular systems?

My concern is color reflectance spectra that show slightly different characteristics under different sample temperatures. I am trying to find out the reason for this and would like to understand what ...
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Is the Brazil Nut Effect quantitative?

The Brazil Nut Effect (a.k.a. granular convection) has a straightforward statistical mechanical interpretation as a system minimizing its free energy, at least qualitatively. What I wonder is whether ...
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Would the thermometer inside an evacuated blackbody hollow sphere show temperature change when we start to heat the sphere?

Would the thermometer inside an evacuated blackbody hollow sphere show temperature change when we start to heat the sphere? Newton law states that an electric or gravitational field does not exist ...
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As of 2021, what is the latest record for lowest temperature?

From what I understand in this article, absolute zero(0 kelvin) is an impossible task. They state that the lowest temperature achieved in the laboratory was 0.1 nanokelvin. The lowest temperature ...

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