# Tagged Questions

Covers the study of (mostly homogeneous) macroscopic systems from a heat/energy/entropy point of view. Maybe combine with [tag:statistical-mechanics].

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### How fast does heat travel via conduction?

I have read this question which seems to ask an identical question, but I'm not sure - it had far too many words I don't understand, let alone the equations. Perhaps someone can answer with a heat-for-...
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### Why is it difficult to mix helium and nitrogen gases?

I recently learned an interesting fact: That it's difficult to mix helium and nitrogen gases in a compressed gas cylinder. Gas suppliers that need to mix the two gases have to rotate the cylinders for ...
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### What does temperature coefficient of resistance depend on?

I tried looking up on Google if there was an expression for the temperature coefficient of resistance(TCR) of a material in terms of other fundamental factors, but couldn't find any. Specifically I am ...
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### Monatomic gas work

Recently I was trying to solve the following problem: monatomic gas expanded from 0.2 to 0.5 m^3 and pressure increased from 404 to 808 kPa. Find work done by gas, heat gained and change in internal ...
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### Negative absolute pressure with positive absolute temperature

Could I ask if the derivative defining pressure $dU \over dV$ or ${∂S \over ∂V}|_{E,N}$can be negative in processes occuring in system not cosmological but statistical(gases or solids or liquids-I ...
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### Is there any experimental setup to test if we are Boltzmann brains? [closed]

I am not sure if this subject belongs to mainstream physics. my question is motivated by the fact that I am not sure we could ever test if we are Boltzmann brains. The same happens with string theory, ...
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### Expansion of solids on heating

I read that when we heat a solid, it expands! Based on circumstances it can expand in area, length and volume! My question is , that do they expand to a certain extent or keep on expanding, if we ...
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### The whole black vs. white T-shirt issue [duplicate]

I was outside with a friend the other day and we ended up talking about clothing choices in the heat, and he repeated the usual statement that one should wear white instead of black in order to stay ...
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### Can temperature be a complex number?

Is it possible for a temperature to be a complex number? I want to say "no" but I can't be so sure. If it is possible I would like to know of an example. I found an interesting article which treats ...
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### Why does the temperature of a gas inside a moving container not increase with velocity?

A rectangular (simplified) container with rigid surfaces, has a certain mass of ideal gas within it, and it accelerates in free space, undergoing rectilinear motion. There are no dissipative forces. ...
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### Definition of 1 calorie

Why has the definition of 1 calorie been taken to be the energy required to heat 1 gram of water from 14.5 to 15.5 degree centigrade at standard pressure? Is there any specific reason for taking the ...
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### Which materials absorb heat?

Which are the materials that absorb heat? and can i somehow convert that absorbed heat into a different form of energy? I am looking into trying to absorb the wasted heat dissipated by laptops,severs ,...
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### does the internal energy and enthalpy of the GAS changes in a free expansion process?

when a balloon kept in an evacuated room is punctured and the ideal gas in the balloon goes on to fill the entire room,does the gas perform any work in this expansion, and is there in any change in ...