Questions tagged [thermal-conduction]
135 questions
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3 answers
Why is rock or metal often cold to the touch but wood or plastic is not?
In a room at normal room temperature, certain materials, such as metal, glass, ceramic, or rock, will feel cold to the touch, but others, such as wood or plastic, do not so much.
Which physical properties do the former materials have in common that…
CPlus
- 1,096
34
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10 answers
Why is transfer of heat very slow as compared to transfer of sound in solids?
If I heat a one-meter long iron rod at one end, the heat takes several seconds to reach the other end, while sound takes fractions of a second. Why is it so?
14
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6 answers
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 a steel ladle in it. When the temperature of the…
Hottestbeef
- 165
12
votes
2 answers
Can a tea light really heat a greenhouse?
It is a common suggestion amongst greenhouse enthusiasts that a long-burning tea light inside an upturned terracotta pot can be enough to keep frost away from plants. Is this possible?
Instinctively, it feels wrong: in winter, a greenhouse does not…
Ian Cox
- 123
11
votes
1 answer
Why haven't we found thermal superconductors?
First of all I want to apologize if this is a stupid question. I'm a layman who's merely very interested in physics, without a degree to my name.
I was trying to research electric superconductors lately (in parts due to the news regarding LK-99, to…
user3106891
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10
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15 answers
How can heat pumps be more efficient than electric/resistive heating?
I cannot understand how a $COP > 1$ does not contradict the laws of thermodynamics (the first one, in particular).
Whatever searches I do, return things like "a heat pump is moving heat, not creating it" .... The answer in my mind is: "Yea, cute…
Cal-linux
- 242
9
votes
6 answers
Cup of warm water suspended in a pot of water held at a steady boil
The question asked by a website is as such (possibly behind a paywall):
A cup of warm water is suspended in a large pot of water held at a steady boil. Will the water in the cup ever boil? Assume that the pot never runs out of water.
The provided…
Shane
- 423
7
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2 answers
Wiedemann-Franz law
The Wiedemann-Franz law states that the ratio of thermal conductivity $\kappa$ and electrical conductivity $\sigma$ for metals fairly accurately obeys $\kappa/\sigma = LT$, where $T$ is the temperature and $L$ is the Lorenz number, whose value is in…
Étienne Bézout
- 581
6
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4 answers
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 heater. But can humans feel cold objects the same…
Ram Rachum
- 271
6
votes
2 answers
Why aren't (domestic) kettles insulated?
In my experience of buying and using (domestic) kettles, I have come across none which are insulated.
The obvious reasons as to why it would be beneficial being that heating time would be reduced, similarly, less power hence money would be required…
Phizzy
- 860
4
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0 answers
Is there relativistic description of the heat equation?
From what I've read, the usual heat equation is not relativistic. This is because the usual heat equation takes the information of temperature differences to be spread instantaneously. This is obviously not compatible with special relativity.
The…
Mozibur Ullah
- 14,713
4
votes
1 answer
Physics behind gold+silver space blanket placement
In the first aid and mountaneering, "space blanket" or "astro foil" is used for protection against cold enviroment or as first aid after burns. There are many different versions of the product. This question relates to thin alumium-based foil of…
Urh
- 143
4
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0 answers
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 famous publication, "On the Irreversible Production…
hyportnex
- 21,193
4
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1 answer
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, is a pattern that keeps going due to natural…
Mel
- 117
3
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4 answers
On the non-quasistatic transfer of heat
Suppose we have two bodies at different temperatures, and we let them interact thermally in such a way that the process is not quasistatic (e.g. two different metal spheres touching). Do we arrive at the same final temperature as if the same spheres…
EE18
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