# Questions tagged [dissipation]

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### Validity of $\mbox{d}H/\mbox{d}t=\partial H/\partial t$ for dissipative systems [closed]

It' well known that in Hamiltonian formalism one has $$\frac{\mbox{d}H}{\mbox{d}t} = \frac{\partial H}{\partial t}.\tag{*}$$ One proof can be found here. Therefore, the total change of energy during ...
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### Can an optical medium be lossless and dispersive?

Occasionally, I come across the phrase "lossless dispersive linear optical medium". How can such a medium be possible mathematically? I mean the real and imaginary parts of the electric ...
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### Would the Moon move away if the Earth were frozen with no liquid tide?

The moon is moving further from the Earth. To the extent that after 600 million years we will no longer enjoy full solar eclipses as it will be too far away to completely block the sun. The reason the ...
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### Output of ventilator and air friction

Imagine you have a ventilator with straight rectangular ventilator blades which are rotated at some small angle from a perpendicular line to the rotating axis. The ventilator has 100% efficiency (all ...
• 11
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### Why exactly (on the level of particles interacting with each other) do things heat up with friction? E.g. airplane from friction with air

Why exactly (on the level of particles interacting with each other) do things heat up with friction? E.g. airplane from friction with air. Also what is the difference between conduction and convection,...
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### Does a single ball undergoing ideal simple harmonic motion count as being in thermodynamic equilibrium?

(Posting this and deleting a previous similar post to make the question more clear.) Suppose we have an isolated system inside a box consisting of a spring and a ball attached to the spring. The ball ...
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