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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PP Chain and CNO cycle relationship

At what temperature would the energy generation rates of the PP-Chain and CNO cycles be roughly equivalent? The dependences are so vastly different that I am wondering how and by what equations they ...
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39 views

Superfluids (meaning, properties)

I am curious as to what a superfluid is? I have seen videos that say that they have zero viscosity, and I know that it means that there is no friction between the layers of the fluid. But what is its ...
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229 views

Why does the system move until equal temperatures are obtained?

In my college level thermodynamics class, the teacher gave us the example of a closed system which consisted of a box thermally insulated. A piston fully divides the box in two parts, and each is ...
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41 views

Temperature in a vacuum made in the lab

Is the thermal energy of a vacuum 0? And, how close to a perfect vacuum can we make in the lab?
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37 views

The meaning of the temperature in the Shockley Equation

In the Shockley equation, which is the model of the $I$-$V$ curve of a p-n junction, what does the Temperature refer to, carrier temperature or lattice temperature? When a p-n junction subjected on a ...
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1answer
93 views

How to heat water to 80°C? [closed]

I'm trying to figure out an easy water to get 80°c to consistently make the perfect cup of coffee. Let's assume room temperature water is 22°c. What is the ratio of boiling water to room temp water ...
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60 views

Is there any relation between temperature dependence of resistance and fermi energy in metals?

Given that the resistance varies linearly with temperature in metals, is there any way we can calculate the Fermi energy from this information?
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49 views

What is the theoretical instantaneous temperature of a gas?

When we measure the temperature of a gas we typically integrate the molecular collisions and wind up with an 'average' temperature due to the sensor comprising a relatively large thermal mass. And ...
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3answers
228 views

100°C = 100 K =?

I'm in first year. Our class is in lesson " Heat and Thermodynamics". While solving a numerical problem of a reversible engine he told us that 100 degree Celsius is equal to 100 kelvin. I inquired but ...
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34 views

100°C =100K = how? [duplicate]

I'm in first year. Our class is in lesson " Heat and Thermodynamics". While solving a numerical problem of a reversible engine he told us that 100 degree Celsius is equal to 100 kelvin. I inquired but ...
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1answer
104 views

Number $g(T)$ of relativistic degrees of freedom as a function of temperature $T$

Let us consider the total number of relativistic degrees of freedom $g(T)$ for particle species in our universe: $$g(T)=\left(\sum_Bg_B\right)+\frac{7}{8}\left(\sum_Fg_F\right)$$ Where the sums are ...
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62 views

why doesn't liquid metal vaporize in a vacuum?

I am wondering why molten metal in a vacuum of electron beam and machines never turns to gas like liquid water does when exposed to a vacuum.
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65 views

How do you calculate/estimate hypersonic leading edge and skin temperatures?

At lower speeds (below Mach 5-ish), stagnation temperature (TAT) is a very accurate proxy for skin temperature. But at mid/high hypersonic speeds (especially in the thin upper atmosphere where mass ...
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31 views

How water anomalies affects the Mpemba effect?

I understand basic explanation of Mpemba effect like this: Distant molecules are easier to realign into new formations. But if we compared two bottles of water like in Mpemba effect and one of them ...
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4answers
63 views

Fall in temperature due to expansion

The following lines are from my book. The gas is heated and allowed to expand at such a rate that the fall in temperature due to expansion is less than the rise in temperature due to the heat ...
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0answers
71 views

How does a heated constant volume flow behave, for an expanding flow tube leading into the free atmosphere

I have a helium gas flow with a flow rate that has been set to a constant value ($0.3\,m^3/h$). It's streaming upwards in the picture, and beyond the upper big red dot position, it meets the ...
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31 views

An interesting question on the mass of a droplet of liquid experiencing the Leidenfrost Effect

Background and Inspiration: I have seen numerous demonstrations of the leidenfrost effect, both on the internet and in my mother's kitchen. But I started wondering about a general case after having a ...
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1answer
108 views

Why is my breath hot when i open my mouth all the way, but cold if I blow like a whistle? [duplicate]

I observed this as when I want to cool my soup I blow like a whistle and when I want to warm my hands I open my mouth more as my breath is warmer now.
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52 views

Is the gas constant really a constant?

For ideal gases we have $$ C_p-C_v=R $$ now the left hand side of this equation is temperature dependent, so how is it possible that gas constant $R$ is temperature independent?
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2answers
72 views

Are black holes hot?

If no light can escape black holes, in my mind they would act as a greenhouse, collecting radiation from the stars or CMB or anything. Or is all this energy just absorbed by the black hole?
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1answer
46 views

Is the size of the universe directly related to its temperature? [duplicate]

The universe was at its hottest when it was at its smallest. As the universe expands, it gets cooler. Is the expansion of the universe the direct cause the cooling? I suppose it would be more clear ...
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1answer
21 views

Cooling effect of sipping

Is the primary action of cooling of a sipped hot fluid explained by the reduced flow of the hot fluid, the air cooling of the fluid as it is sipped or another factor?
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1answer
46 views

Why does hot air rise?

Why does hot air rise? I did an experiment: I made a model of hot air and cool air with marshmallows and toothpicks. The hot air had more volume than the cold air. Then, I weighed it. They both ...
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Given temp and conductivity can I back-calculate to resistance, in order to plug in a new temp value and calculate a more accurate conductivity?

Background: I used a small CTD (conductivity, temperature, depth) recorder to log a series of dive profiles in a mixed coastal estuary. The recorder logged observed temperature and conductivity every ...
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45 views

What are the Fermi and Debye temperature constants?

What are the Fermi temperature and Debye temperature constants? We were discussing these in class and I don't fully understand what these constants are or why we have them. Can anyone explain?
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140 views

How hot is your photon?

This question comes from my answer to the question Can a cubic meter of space at absolute zero have any object with mass inside? and the related discussion under it. To summarize, I stated that the ...
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3answers
353 views

Can a cubic meter of space at absolute zero have any object with mass inside?

I ask this question because, I have seen many places where they say the average temperature of the universe is some 2 degrees K and this somehow relates to mass present within a given volume of space. ...
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29 views

absolute minimum vs absolute maximum [duplicate]

there is such a thing as a absolute minimum temperature defined by At the physically impossible-to-reach temperature of zero kelvin, or minus 459.67 degrees Fahrenheit (minus 273.15 degrees ...
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44 views

Why does a thermal memory need a thermal bath?

In the article "Thermal Memory: A Storage of Phononic Information Phys. Rev. Lett. 101, 267203 – Published 29 December 2008" it's said that a thermal memory need a thermal bath, similar to a power ...
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150 views

Is my conceptual understanding pertaining to heat & temperature correct?

From what I've understood: Heat is the total sum of translational energy possessed by individual atoms in an object. Temperature is the average translational energy possessed by individual atoms ...
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16 views

Trying to determine transient response of air conditioned room

I have an air conditioned room which intakes airflow at temperature $T_{in}$ at a mass flow rate $\dot m$. The air leaks out of the room at mass flow rate $\dot m$ and temperature $T_{room}$. The room ...
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3answers
214 views

Determining a temperature increase from heat energy [closed]

A 15.0g bullet traveling horizontally at 865 $\frac{m}{s}$ passes through at a tank containing $13.5$kg of water and emerges with a speed of $534\frac{m}{s}$. What is the maximum temperature ...
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1answer
63 views

Linearity of thermal expansion of metals?

I am having to do a path length correction for a metal tube (stainless steel 316, 16ppm/C) from 0-100 degC. I need to correct to within approximately 1 ppm. How much do typical engineering metals ...
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1answer
148 views

How does the entropy change during the cooling of a hot coffee in a cold cup?

The second Law of Thermodynamics states that entropy always increases in the universe: things become more disorganised. This means, that if I have a hot coffee in a cold cup, then the heat will ...
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PCF based temperature sensor [closed]

how to calculate relationship of refractive index And temperature for liquids in optics and what are the methods?
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105 views

Why don't the collisions of the particles in a gas affect its temperature?

Temperature is defined as the mean kinetic energy of the system. Now the particles are constantly colliding with each other; as a result of which kinetic energy of each particle changes. ...
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Solar plants and energy conservation

I'd like to apologise if this question is stupid or if it was asked ten thousand times - I haven't found an answer to it. Quite possibly due to mediocre English or abominable knowledge of physics. ...
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4answers
191 views

Relation between temperature and pressure?

I was just working on a special question but I ignored the effect of temperature on it and now it becomes very important to me. What is the relation between Pressure and Temperature? Suppose we ...
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Constant volume gas thermometer

Well, in the notes I took in thermodynamics' class I have a graph that plots Pressure of boiling point $P_b$ over Pressure of freezing point $P_f$ at constant volume in terms of Pressure of boiling ...
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2answers
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Why do we call a white led with high color temperature “cool”?

one can buy LED bulbs with defined color temperature. why cool white = many kelvins (= high temperature?) why warm white = few kelvins (= low temperature?)
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Temperature as the independent variable of Lagrangian

I was thinking about applications of the Lagrangian and I started to toy with some ideas and tried to come up with interesting twists. Immediately I thought it would be interesting to use temperature ...
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56 views

Why is temperature vibration?

Why do the atoms in a crystal vibrate at finite temperature?
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81 views

Increase in Solubility of a Gas with an Increase in Temperature

On the UC Davis ChemWiki I read, "some gases have an increase in solubility with an increase in temperature." I understand why this is applicable to solids in liquids such as water, but why is it ...
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Thermometric Properties

A thermocouple thermometer with 10 ohms of resistance is calibrated with its hot junction and cold junction immersed in steam and melting ice respectively. An EMF of 5.6mv is measured. This ...
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Gay-Lussac's Law & the Patriots

This may be a question better suited for xkcd what if? section...but here goes: with all the hoopla around the patriots / colts game and allegations of cheating by deflating footballs, I've read/heard ...
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3answers
103 views

Average temperature of the universe

Is it possible to define some average temperature of the universe? If yes, what fixes this temperature and how t estimate today's temperature? Is it different from the temperature of the black-body ...
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1answer
74 views

Could the uncertainty principle theoretically be violated at 0 K? [duplicate]

Ok so please excuse me if the following mental argument is completely ridiculous or obviously flawed :P I was reading about how, even at 0 K (assuming we could experimentally reach such a ...
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1answer
38 views

Blowing on a hot liquid [duplicate]

Lets say you have a nice bowl of piping hot soup. You use your spoon and take a sip and realize its too hot. So you blow on it a few times and now its cooled enough that it doesnt burn your mouth. ...
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0answers
44 views

Finding the temperature of Earth from temperature of Mars and its distance from Sun [closed]

I am to compute the temperature of planet--in fact I've already found out it's Earth--knowing only: the surface temperature of Mars (210 K) and its distance from Sun (1.524 AU) and of course ...
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117 views

How hot is Plutonium-238 in Radioisotope Thermoelectric Generators (RTGs)?

As I understand it, Plutonium-238 is used to provide power through heat generation in radioisotope thermoelectric generators. My question is... how hot is a pellet of Plutonium-238? Does the heat ...