Questions tagged [equilibrium]
Equilibrium is the condition of a system in which all competing influences are balanced. These can range from forces (static/dynamic equilibrium), to chemical processes (chemical equilibrium) and temperature gradients (thermal equilibrium).
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A paradox while explaining the equilibrium of books
An even number of books (say four) are held in the manner shown in the figure. It is obvious that if we apply a large force inwards, we can increase the normal force, and hence the friction which ...
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Equilibrium in physics
We know that harmonic oscillator or pendulum will not reach a equilibrium at infinite time. But why a system of gas molecules reaches equilibrium (entropy of an isolated system will tend to increase ...
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Two interacting blackbodies (one inside another) - when will thermal equilibrium be attained? [closed]
As I understand it, an ideal blackbody absorbs (and subsequently starts emitting) all incoming radiation. In typical setups like determining a planet's temperature given its albedo and distance from a ...
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Statics problem from classical mechanics
I was solving David Morin's book on classical mechanics.
In the solution for the second part of the "a" part of the question, why is the normal force defined as $Ndθ$ and not just $N$? Is ...
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Intuition for imaginary time Greens function
I understand that $$G^M(0,0^+) = \operatorname{tr}\{\rho O_2 O_1\}$$ (I am not putting hats on the operators here because they don't render in the correct position) is simply the expectation value of ...
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Thermodynamic work and potential functions
I was reading about the maximum thermodynamic work of a system (Z) that is going to equilibrium.
\begin{equation}
dZ = dU + p_0 + T_0dS
\end{equation}
I then came across the thermodynamic potential ...
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Why must solids in equilibrium become crystalline?
In Landau's Statistical Physics's analysis of solids, he begins with the remark that solids are caracterized by their atoms' small oscillations about equilibrium positions. However, he states that ...
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How does this tensegrity table work?
I have assembled below a desk toy which seems to defy laws of physics at first glance (objects can be placed on top of it up to a certain limit, since it is already under strain).
The toy is in fact ...
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An object is connected to the end of a spring and is immersed in water. What are the forces acting on the object? [closed]
The actual question is
A copper piece of mass 10g is suspended by a vertical spring. The spring elongates 1 cm over it's natural length to keep the piece in equilibrium. A beaker containing water is ...
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What is the difference between a reversible process and an equilibrium? [closed]
I am confused about the differences between a reversible process and an equilibrium when considering their energy aspect.
Here is what I know so far.
(1) Equilibrium and Reversibility
Equilibrium ...
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Serway & Jewett's definition of rotational equilibrium
On p. 364 of Physics for Scientists and Engineers (9th ed.), Serway and Jewett define a rigid object to be in rotational equilibrium if it has an angular acceleration of zero. They then state that a ...
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How do differently colored objects reach the same temperature if they are completely isolated together?
Imagine a perfectly reflective container, filled with vacuum and two bodies with different colors, i.e. they have different emissive and absorptive properties. The bodies don't touch each other or the ...
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Pressure difference between a box and the outside atmosphere
Say I have a box of volume $V$, with an ideal gas inside it with temperature $T_b$. I don't know the number of particles inside it. The box is surrounded by the room's environment, which has ...
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Investigating the stability of a wooden block
Consider the above experimental design. At the end of the strip, at point $p$, a mass $m$ is attached, the stability of the wooden block above is determined by the angle $θ$ at which the block topples ...
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Apparent inconsistency with Maxwell-Boltzmann energy distribution
The Maxwell-Boltzmann distribution for the kinetic energies of particles is given as ( https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution#Distribution_for_the_energy )
$$f(E) = 2 \...
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Is the spontaneous flow of heat to thermal equilibrium an explicit law or is it implicitly assumed in thermodynamics?
This sounds like a really daft question, but I am trying to clarify details on foundations on thermodynamics to myself, which will involve asking really (seemingly) basic things.
When you have two ...
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Why equation 5.29 in Schroeder's Thermal Physics is not equal to 0?
In Schroeder's "An Introduction to Thermal Physics" in section 5.2 (page 161), Schroeder considers the case of a system that is in thermal contact with a reservoir that is at a constant ...
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Given state $P$, does the set of all forward adiabatic processes and reversed adiabatic processes reach all states in the state space?
Let $A$ be a thermodynamic system and let $\Sigma$ be its state space. By the state postulate, if $A$ has $n$ two-way work channels (i.e. ways in which work can be done both positively and negatively ...
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Understanding the relationship between $\Delta G$ and $K_p$, $K_x$ and $K_c$
Upon reading the chapter about equilibrium from my physical chemistry book, I was convinced that
$$ΔG= -RT \text{ln}(K_p) \tag{1}$$
and that
$$K_p = K_x (P^{\sum v}) \tag{2}$$
where $K_p$ is the ...
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Water level in pipe higher than surrounding body of water
I had a question about water pressures and level. We've recently drilled a near vertical hole underground 130m deep by 400mm in Dia into flooded lower underground workings as part of a de-watering ...
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What regulates the size of our atmosphere?
Our atmosphere is only about 100km thick before the official start of space. That is a mere 1.57307% of the radius of Earth (6,357km). The difference between the gratitational force at sea level and ...
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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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Why does Equilibrium shifts towards more dense phase while increasing pressure for phase change Equilibrium?
I recently read that when pressure of system in phase change equilibrium is increased, it shifts towards denser phase. So, in case of Melting of ice, increase in pressure results in shift towards ...
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Doubt regarding proof of Earnshaw's Theorem using Gauss's theorem
While proving Earnshaw's theorem using Gauss's theorem, we consider a small sphere surrounding our test charge, and apply Gauss law on this sphere, stating that field from all external charges must ...
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Why charges reside only on the surface on conductor?
I wonder why charges reside only on the surface on conductor?
And I read this question and the answer to it:
Why charges reside on the surface on conductor?
https://physics.stackexchange.com/a/210634/...
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Charge separation equilibrium equation for non-rotating blackhole at Eddington limit with spherically symmetric accretion?
What is the formula for equilibrium charge on a non-rotating black hole with spherically symmetric hydrogen-1 inflow at the Eddington limit of luminosity based on photon scattering acceleration of ...
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Classification of equilibrium configurations for particles subject to elastic force constrained on a circle
I am interested in classifying all the possible equilibrium configurations for an arrangement of $l$ equal point particles $P_1, P_2, . . . , P_l$ $(l > 2)$ on a circle of radius $R$ and centre $O$....
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Lami's Theorem Problem
Lami's Theorem states that the magnitude of each force in an equilibrium state consisting of three coplanar, concurrent forces acting at a point is directly proportional to the sine of the angle ...
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Equilibrium constellations of classical point charges in hollow conductors
As far as I know, in free space there can be constellations of $N$ point charges in electrostatic equilibrium (albeit unstable equilibrium) for all $N$ except $N=2$.
Some discussions here already ...
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The forces acting on the tensegrity structure
Are these the only forces acting on the body. I assumed the COM to be somewhere there in between. since the tension in main string doesnt perfectly coincide with COM theres a small torque being ...
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