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Why does capillary in gas thermometer have a temperature and pressure gradient?

I have been learning thermodynamics using Heat and Thermodynamics by Zemansky, in which he mentions The gas in the capillary connecting the bulb with the manometer has a temperature gradient, that is,...
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Does the isotropy definition of a perfect fluid imply no heat conduction?

Weinberg defines a perfect fluid (Chapter 2, Section 10) as one where each fluid element appears isotropic in a reference frame moving with that element. From the definition of the stress-energy ...
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Does Pipe Temperature Directly Correlate To Water Temperature? [closed]

I need to know if just by taking a boiler flow pipe temperature that will tell me the water temperature that is flowing through the pipe. For example if the water from the boiler travelling through ...
Ross Hayward's user avatar
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2 answers
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Entropy change of an isolated system consisting of two thermally conductive blocks of equal isochoric heat capacity at different temperatures

A classic example considered in most introductory treatments of elementary thermodynamics consists of two thermally conductive (e.g., metal) blocks placed in thermal contact. In particular, I find ...
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7 answers
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Should I hold a baby formula bottle to cool it down faster?

This is an interesting and somewhat surprising physics problem - holding a hot object in your hand will cool it down faster, even if the air around is colder. I guess that 90% of people would be ...
daniel.sedlacek's user avatar
2 votes
1 answer
33 views

Estimating Heat transfering by measuring [closed]

Consider the setup with closed chamber with two flat metal objects with know dimensions. The first object can be heated or cooled by peltier module and the second one is placed on top of the first one....
elektro_vujke's user avatar
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Definition of convection heat transfer not unambiguous? [duplicate]

What is actually the definition of convection in the context of heat transfer, if there is one? Wikipedia states: Convection (or convective heat transfer) is the transfer of heat from one place to ...
feliszingiber's user avatar
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1 answer
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Heat equation two stage process - Additivity? some other approach?

I'm struggling a bit how to apply a standard solution to the heat equation to my own practical problem. I have some intuition, but do not know whether this intuition is justified. I don't understand ...
W_vH's user avatar
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Why clothes keep us warm?

I want to understand why clothes keep us warm. I understand that they reflect back thermal radiation and also trap air thus significantly reducing cooling due to thermal convection. My question is, do ...
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Heat exchange speed of two liquids separately vs their mixture

I'm quite oblivious about basic high school physics, so pardon my misuse of terms and inability to google the answer. I want to solve a puzzle that I face in my daily routine. Suppose I want to make a ...
Alexey S. Larionov's user avatar
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1 answer
47 views

Why are absorbing bodies hotter over time than reflecting bodies?

I recently learnt about energy transfer by EM Waves and came across the formula for momentum transfer, i.e. Δp = U/c → perfect absorption Δp = 2U/c → perfect reflection then why do absorbing bodies ...
Manukrishnan P's user avatar
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Temperature of plasma sputtering magnetron

This question is in regards to DC magnetron sputtering for coating surfaces. My main goal is to determine how much heat will be seen by the anode, cathode and the target. As well as to determine what ...
CakeMaster's user avatar
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Thermal resistance in heat transfer

Can a material experiencing heat generation be represented by thermal resistance and  included in a circuit analysis? If so, why? If not, why not? Consider a case with the solid cylinder with the heat ...
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Rate of heat flow through rod of variable conductivity

Incase wher we have an object( a rod ) with its conductivity not uniform say varying with temprature. Then will heat flow through it at same rate from every cross section of the object?
Mainframe's user avatar
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2 answers
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Glass having huge thermal mass when stirring drinks

In the book "Liquid Intellegence: The Art and Sience of the Perfect Cocktail", David Arnold says this: My question is how the glass affects the chilling? What does he mean by the glass ...
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Lumped body analysis

$k$ - thermal conductivity, $h$ - heat transfer coefficient, $\rho C_p$ - Volumetric heat capacity, $T$ - temperature $T_\infty$ - Temperature of exposed cooling surrounding environment Consider two ...
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At what circumstances is Nusselt's theory of evaporating falling films valid?

Nusselt's theory of evaporating falling films assumes no convection and neglects the effect of inertia. At what circumstances is that valid? Any books or articles that discuss this in depth would be ...
Lost Bubblegum's user avatar
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How to deal with temperature drift when computing thermal conductivity with molecular dynamics?

Background In the $NVE$ ensemble, thermal conductivity, $\lambda_T$, can be computed from molecular dynamics (MD) using the Green-Kubo relation (Allen and Tildesley) $$\lambda_T = \frac{V}{k_B T^2} \...
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Fully coupled thermal-stress analysis in Abaqus/Standard- equations

I'm simulating a fully coupled thermal-stress problem with linear elastic material in Abaqus and comparing the results with my own implementation of the same problem in FEniCSx. The weak form in ...
MPa's user avatar
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2 answers
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Physics of microwave oven

I am looking for a definitive discussion of the physics of microwave oven - I mean I would like to see actual evidence in favor of this or that explanation, rather than just popular physics/...
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Why some materials expand linearly on heating while others have areal and volumetric expansion for the same temperature difference?

Why some materials expand linearly on heating while others have areal and volumetric expansion for the same temperature difference? What actually cause materials to expand?
Vinay5101's user avatar
1 vote
3 answers
82 views

Heat equation in 1D with Robin conditions [closed]

I am tasked with analytically solving the boundary value problem as follows: the 1D heat equation for temperature $T \equiv T(x,t)$ in a solid extending from $x = 0$ to $x = L$ and located in air at ...
Dasty's user avatar
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General differential equation for Energy transfer

In my textbook of Fundamentals of Momentum, Heat, and Mass Transfer by Welty, it is said that $$\nabla \cdot k\nabla T + \dot q + \Lambda = \rho \frac{Du}{Dt}+\rho\frac{D(gy)}{Dt}+\mathrm v \cdot \rho ...
Lime nut's user avatar
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1 answer
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Approximating the temperature of the wall of the heating jack of a reactor

Suppose we have a reactor containing some fluid that we heat through a heating jacket containing some other fluid. I am interested in approximating the temperature of the wall of heating jacket. I ...
MathEnthusiast's user avatar
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1 answer
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Why slow compression with conducting walls should be isothermal?

I know that for an isothermal process heat transfer is necessary so process should be slow and walls should be conducting for heat transfer to occur as a process cannot be isothermal and adiabatic at ...
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Conduction in liquid and gas

Is this condition correct, "if liquid and gas heated from top, then it will be possible for 'conduction' to occur" ? One reason i can think is : when liquid or gas is heated from sideways or ...
Cerebral cortex 's user avatar
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Conduction Heat transfer through cylinder, the $\ln(r_2/r_1)$ term

For steady state, radial conduction heat transfer through a cylinder, all textbooks show a term $\text{ln}(r_2/r_1)$ in the denominator $[q = (2*\pi*k*L*\delta T)/\text{ln}(r_2/r_1)]$, where $r_2>...
Jahin Parvez's user avatar
14 votes
6 answers
3k views

Can the temperature of a steel ladle in boiling water exceed the temperature of the water?

I'm debating about this problem with my friends (they and I majored physics. But I think it's not a trivial question.) The problem is : The water in the pot is boiling by the gas stove, and there is ...
Hottestbeef's user avatar
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Lee's Method for measuring conductivity of a poor conductor

I have taken a lab course this semester and one of the experiments is the Lee's disc method to determine the conductivity of a poor conductor. For anyone unfamiliar with the experiment, this is the ...
Preetham Karki's user avatar
1 vote
1 answer
64 views

How to find time it takes to heat centre of a sphere to a certain temperature? [closed]

I'm a high school senior planning a mathematical exploration project where I am aiming to answer the question: I have a spherical ball of dough, which is uniformly at temperature 25 degrees Celsius. I ...
Brian Yu's user avatar
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1 answer
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Peltier Thermoelectric Module - Water Cooling

My questions concerns calculations about a Peltier Thermoelectric Module for the cooling of water between an inlet and outlet. The Peltier water cooling module I am referring to is the following: ...
Johmi's user avatar
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1 answer
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How to measure actual conductive & convective losses inside an enclosed container?

I've been studying convection and come across empirically-derived formulas for calculating the Nusselt number for various geometries. For my particular use case, I'd like to measure the actual ...
Cloudyman's user avatar
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1 answer
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How to modify heat conduction equation when air is not at rest?

The heat conduction equation is usually written as $$\frac{\partial T}{\partial t} = \alpha \vec \nabla^2 T$$ But what if a moving air parcel is considered? The standard derivation of the equation ...
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4 votes
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Why Onsager's formulation of thermoelectricity is better than Bridgman's?

General comment: despite the longish historical introduction this question is not about the history of physics but rather about a specific conceptual problem in physics. Following Bridgman in the ...
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Time constant for diffusive process with radiation and convection

I'm studying the thermal comportement of a "mass stove". I would like to do a materials selection. My first constraint is to have a temeperature of my "mass" between a lower and an ...
Dasty's user avatar
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6 votes
4 answers
2k views

Can people feel the low heat radiation from very cold surfaces?

Here's a thought experiment about the way that heat is transferred through radiation. Humans can physically feel when a hot object radiates heat on them, such as a campfire or an infrared-based space ...
Ram Rachum's user avatar
1 vote
2 answers
113 views

Thermal radiation in hollow sphere

I have been asked to calculate the time taken for a highly conducting hollow sphere to cool down from a certain temperature say $\theta_1$ to a temperature $\theta_2$ ($\theta_1, \theta_2 > \...
QuantumQuipster's user avatar
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1 answer
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How do I calculate the rate of heat loss from an enclosure when I have a plot of temperature vs time and the enclosure's material details? [closed]

I have an enclosure running an ON/ OFF temperature control system. The below graph shows internal air temperature over time. I have the raw data providing actual values. I have the dimensions of the ...
Dale117's user avatar
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1 answer
46 views

Heat transfer vs. Volume transfer [closed]

Apologies in advance if this has been addressed before... it's something if a daily puzzle during my morning ablutions and I haven't gotten a handle on it yet. Consider the hot water pipe from my ...
keshlam's user avatar
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Anisotropic heat flux from anisotropic shape

Expanding the discussion in Thermal conductivity from the mass distribution of an object Is it possible to have asymmetric heat flow with linear materials with temperature independent thermal ...
Caetes's user avatar
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How much longer to thaw an elephant than a chicken? [closed]

Twenty-five years ago I came across this question on a physics olympics exam and I've never really worked out a satisfactory answer... How much longer does it take to thaw an elephant than a chicken? ...
nicolaskruchten's user avatar
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2 answers
177 views

Heat diffusion equation in terms of entropy?

Ok, I am very rusty in thermodynamics. In fluid mechanics books, you can find the heat transport equation in terms of temperature $T$: $$ \rho c_p\left(\frac{\partial T}{\partial t}+\boldsymbol{u}\...
BitterDecoction's user avatar
0 votes
1 answer
43 views

Fourier Heat conduction law and two insulated layers heat conduction rate [closed]

If we apply Fourier heat conduction law to a system of two insulated layers joined together, of the same area, can we always assume that the rate of heat transfer between the layers will eventually ...
GedankenExperimentalist's user avatar
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Difference of the Transmission Coefficient between Thermal and Charge Conductance by Nonequilibirum Green Function Method

The equation 57 in the reference [Jian-Sheng Wang, Jian Wang and J. T. Lu, Quantum thermal transport in nanostructures, Eur. Phys. J. B 62, 381 (2008)] explains the the transmission coefficient for ...
Kieran's user avatar
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1 answer
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Thermal conductivity from the mass distribution of an object

Thermal conductivity is a property normally related to material. But it is also possible to relate it to objects. Consider two objects of different shapes made by the same homogeneous material. How ...
Caetes's user avatar
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1 vote
1 answer
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Modelling of a heat exchanger [closed]

re mathematician so im so lost... Any help will be very appreciated!
Guillermo García Sáez's user avatar
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1 answer
67 views

Do linear expansion, area expansion, cubical expansion all occur simultaneously in a metal rod when heated?

Consider a metal rod being heated. As metal rod is a good conductor, it spreads heat all through it. If so I think all the linear,area and cubical expansion takes place simultaneously practically. Am ...
ayyappan muthukrishnan's user avatar
1 vote
0 answers
43 views

What's the percentage/relationship of evaporative cooling applied to the liquid by an evaporating/expanding gas?

The example below is simply to provide illustration of the problem. This isn't a homework question. I'm trying to visualize the relationship between liquid and gas at the boundary and I'd appreciate ...
MaximumSkeptic's user avatar
4 votes
1 answer
384 views

Can land breezes be an example of perpetual motion?

Since perpetual motion refers to a never-ending motion with no external energy provided whatsoever, can land breezes or sea breezes be an example? Or perhaps even trade winds, since this, I believe, ...
Mel's user avatar
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Is there physical significance to the Gateaux derivative of entropy?

Is there any physical "force" generated by a difference in entropy or information between two regions? There is some confusion between thermodynamic entropy and information entropy, but one ...
Jackson Walters's user avatar