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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Why has Earth's core not become solid?

The Earth is billions of years old, yet its core has not yet cooled down and become solid. Will this happen in the foreseeable future?
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3answers
202 views

What is planetary surface temperature given constant sub-surface temperature?

If a planet of radius $R_1$ has a constant sub-surface temperature $T_0$ at $R_0<R_1$, what is the long-term equilibrium surface temperature $T_1$? Say we assume constant thermal diffusivity of ...
0
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4answers
37 views

What happens when I place an object of certain temperature in space ? Does it loose its entire heat energy?

Can i obtain absolute zero temperature this way? And let's assume there is no cosmic microwave background and also assume that there is a way to shield the object from any heat source, such as the ...
2
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0answers
21 views

Does the surface of austenitic steels have an especially “dynamic” phase somewhere between 100 and 200 Celsius?

There is lots of kitchen lore about pans. One popular concept are the "pores" of a steel pan surface, which are the reason why food sticks to the pan when it's not heated properly. I don't know much ...
4
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1answer
43 views

What is the temperature of the clear night sky from the surface of Earth?

Before you all jump in with 2.73 K or thereabouts, this is more of an experimental question. It will obviously depend on humidity and radiation being scattered back towards the surface of the Earth. ...
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Will Ice Cubes Form Quicker when Made from Hot Water or Cold Water? [duplicate]

When you put water in the freezer you can make Ice Cubes. But does the time taken for these Ice Cubes to form decrease or increase when the water which is used is hotter or colder?
6
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2answers
127 views

How does the Sun's magnetic field continue to exist at such high temperatures?

The temperature at the surface of the Sun is apparently well above 5000 C; I'm assuming the layers beneath the surface may be even hotter. At school, we learned that heating a metal beyond a certain ...
3
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1answer
43 views

Relation between Entropy and Temperature

Entropy is defined in my book as $S = \frac{Q}{T}$. To derive the formula it says that entropy should be directly proportional to the heat energy as with more energy the particles would be flying all ...
2
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1answer
37 views

What does a hot, optically thin gas *look* like?

In another question I tried to answer what a sample of the Sun's photosphere or core would look like, if it could be brought into the lab. Here is a broader question - if I have a small inert ...
0
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0answers
14 views

The initial presumed temperature of the universe is derived from data?

When people mention the BBT (*) they assume that it is hot. As late as 1988 it was scientifically proposed a cold BB model (WP) The initial presumed temperature of the universe is derived from ...
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1answer
56 views

Temperature limit of the increase in heat

If the sun is the hottest known thing to humans is it possible to have a temperature greater than the sun?.
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0answers
54 views

Why does hot food give off vapor?

Does your food melt and then boil to give off this gas? What is the vapor here?.
0
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0answers
24 views

How does heating in the atmosphere look above 100 km

I have tried without luck to find a graph of temperature change through the atmosphere that goes further up than about 100 km. On this graph: (Source: ...
0
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2answers
79 views

Will heating up an object increase its mass? [duplicate]

According to the $E=mc^2$ equation, will an object whose thermal energy (temperature) rises also weigh more? And by the same token, will the mass of an object decrease as its temperature approaches ...
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3answers
835 views

What is meant by the temperature of the CMB?

This is what I commonly read: The CMB came to existence when atoms where formed and photons weren't constantly absorbed anymore. In other words, the universe became "transparent". Because of the ...
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2answers
36 views

Why does room temperature water and metal feel almost as cool as each other?

From what I've read about heat, temperature and conductivity, I understand that the reason water at room temperature feels colder than most other things at the same temperature (like wood, air, ...
0
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1answer
64 views

Temperature of the surface of the sun? [closed]

I recently had an exam question that asked for the temperature at the surface of the sun. The question is The equation I believe you have to use is The Q/t is the radiant power produced by the ...
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0answers
25 views

How is the bandgap reference diode so accurate? (temperature changes bandgap?)

I am studying about bandgap references (wiki). As a black box approach, (from what I know) it can be seen as a system which gives a stable voltage reference irrespective of the highly varying ...
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2answers
133 views

Balloon gas temperature experiment in water

In this problem set I have a passage that describes an experiment that looks at the changing temperature as an air filled balloon rises to the surface from the bottom of a water filled tank. The graph ...
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1answer
46 views

Physical significance of temperature

Some books say when heat flows into a monatomic gas at constant volume, all of the added energy goes into an increase in random translational molecular kinetic energy. But when the temperature is ...
2
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1answer
58 views

Why does air feel cooler when blown through a small hole and warm through a big one? (for example from a mouth) [duplicate]

I hope the question is clear enough and I'm sure that you can try this thing quite easily yourself. When I blow air from my mouth to my palm through a small opening, I feel cool in my palm, but its ...
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1answer
70 views

Heat Equation with In-Depth Radiation Exact Solution

I am looking to solve the heat conduction equation in a semi-infinite solid with in-depth radiation on the domain $-\infty < x < 0$. The governing equation of this problem is: $$\rho c ...
0
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3answers
48 views

Change in energy ideal gas

I am supposed to calculate the change in energy upon changing both the temperature from $T_1$ to $T_2$ and the volume from $V_1$ to $V_2$. Now I was wondering whether this solution is correct: We ...
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1answer
41 views

Heat equation with heat radiation and heat transfer

If I want to calculate steady temperature distribution on a one-dimensional stick, and I need to consider both the heat radiation and heat transfer, then my equation will be in the form: $$ ...
2
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2answers
65 views

First law of thermodynamics [closed]

In the first law of thermodynamics, we learned that $W$ and $Q$ are path-dependent quantities, but how are $Q$ and $W$ defined? I mean $W = \int_{\gamma} p(s) ds$ would be one possibility, where ...
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2answers
32 views

Why isn't there a net force when two rods touch each other?

This is a problem from Beer and Johnston's Mechanics of Materials (Amazon link). There's a problem in which there are two rods of different material, area, and length. The rods are fixed to walls, ...
2
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2answers
62 views

What would a graph of temperature increase of a cup of water in a microwave look like?

My lunch had been in the microwave for a minute or so, and I was wondering if I took it out 10 seconds early, would the amount of temperature it increased in that 10 seconds be more significant, less ...
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2answers
170 views

Arrhenius Fit: Linear or exponential form?

I have a seemingly easy question about performing an Arrhenius fit to the equation $$y = A \times \exp \left( -\frac{E_A}{RT} \right)$$ I can either fit this in the exponential form using a ...
0
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2answers
229 views

Temperature in a Voltaic Cell

The potential difference across a voltaic cell varies with temperature. But my question is whether the voltage increases or decreases as temperature rises. According to the Nernst equation, the two ...
3
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0answers
29 views

Question on finite temperature field theory

In quantum field theory at zero temperature, the expectation values of operators are taken with respect to the vacuum. Is it the case that in quantum field theory at finite temperature, the ...
0
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1answer
47 views

What is the overall rate of heat conduction through two pipes of different dimensions if the thermal conductivity is not constant?

I am trying to work out how I would find the rate of heat transfer through two pipes made of the same material that are joined at their ends but which have different cross-sectional areas and lengths. ...
0
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2answers
89 views

Temperature coefficient of resistivity (resistance) in function of temperature

If I'm correct, the definition of the temperature coefficient of resistivity at a certain reference temperature is the derivative of the resistivity in function of the temperature, divided by the ...
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3answers
68 views

Proper way to write the units to indicate that they include an offset?

Past a certain point of complexity, I get rather confused with physical units, so I am asking a physicist for help. I have a code that represents temperature, with a resolution of [0.5 °C], whose ...
4
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1answer
28 views

Calculating the angular power spectrum of a section of sky

To calculate the angular power spectrum $C_l$ of the whole sky, one uses the variance of the coefficients of the spherical harmonics in the temperature fluctuation field. I.e. $$C_l = ...
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2answers
141 views

Reducing the evaporation of water at room temperature

Water drops kept on different surface evaporate after a few minutes. How can I reduce the rate of evaporation of these drops? Can I add some additives which suppress evaporation?
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0answers
18 views

How to calculate precipitation chance with basic weather data?

I would like to know if there is any algorithm which allows us to calulate precipation chance with following data: temperature, humidity, illuminance (in lux) and pressure. I've searched it in google, ...
0
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1answer
53 views

How does temperature affect the ability of materials to catch fire and keep burning? [closed]

While I'm asking a general question, and will appreciate all answers, the reason for asking this is that I am making a game that will include temperature, among other features, and I'm wondering how ...
4
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3answers
290 views

Existence of negative temperatures and the definition of entropy

How negative temperatures can be possible has been treated on StackExchange before (several times in fact), but in light of some recent academic discussion, most of these answers seem to be possibly ...
0
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1answer
50 views

How to convert cc to bar?

In astronomy/astrophysics, medium density is often given in cc, particles per cubic centimeter. Also, the temperature of the medium is usually given, in Kelvins. For some materials the melting point ...
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1answer
35 views

Why doesn't the temperature of fluid flowing in a pipe increase if the flow speed is increased ?

I have learnt that the temperature of something is a direct measurement of the kinetic energies of the molecules in it. Going by this argument, if the flow speed of fluid is increased in a pipe, and ...
6
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2answers
130 views

Was the Big Bang actually cold?

As I understand, from watching the Discovery Channel, the total amount of energy in the universe is zero. As such, people like Hawking explain that the universe can be created out of nothing ...
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1answer
47 views

Defintion of temperature without thermal equilibrium condition

Is temperature only defined in thermal equilibrium? Then how can we explain heat flow by temperature differences?
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5answers
416 views

Integrating factor $1/T$ in 2nd Law of Thermodynamics

How would you prove that $1/T$ is the most suitable integrating factor to transform $\delta Q$ to an exact differential in the second law of thermodynamics: $$dS = \frac{\delta Q}{T}$$ Where $dS$ is ...
2
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2answers
216 views

Temperature on the surface of the sun calculated with the Stefan-Boltzmann-rule

In a German Wikipedia page, the following calculation for the temperature on the surface of the Sun is made: $\sigma=5.67*10^{-8}\frac{W}{m^2K^4}$ (Stefan-Boltzmann constant) $S = 1367\frac{W}{m^2}$ ...
0
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1answer
35 views

Lattice and carrier temperature

If I hold a semiconductor sample at a certain temperature $T$, its lattice temperature $T_l$ will equalize: $T_l=T$. But how is this lattice temperature related to the carrier (electron or hole) ...
3
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1answer
70 views

Are Matsubara states pure states?

Generally in a non-interacting QFT one can solve the Klein-Gordon equation to get a (complete) set of states $\frac{e^{i\omega_k t-ikx}}{\sqrt{2\omega_k}}$. It is not clear to me how to construct the ...
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7answers
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Is it possible to “cook” pasta at room temperature with low enough pressure?

It is known fact, that boiling point of water decreases by decreasing of pressure. So there is a pressure at which water boils at room temperature. Would it be possible to cook e.g. pasta at room ...
0
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0answers
14 views

Will a sodium bell ring clearly after being submerged in liquid nitrogen?

Lead is fairly soft at room temperature but rings clearly when cooled to liquid nitrogen temperatures. Sodium is even softer. If cooled to liquid nitrogen temperature, could it also ring?
3
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1answer
48 views

Why is there not a delta here in this formula about temperature changes

I have been taught and have seen this formula many times $$Q=m\cdot c\cdot\Delta T$$ Where $Q$ is the internal energy, $m$ is the mass, $c$ is the specific heat and $\Delta T$ is the temperature. ...
11
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1answer
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Why does my jam often “fall up”?

I often get my jam out of the refrigerator, and it looks like this: That is, all the jam has gone to the top, looking as if the jar has been sitting upside down. However, this happens fairly ...