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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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 ...
Kintoke 's user avatar
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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 ...
Darcy Cox's user avatar
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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 ...
Peter R. McMahon's user avatar
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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 ...
Maximal Ideal's user avatar
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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 ...
Parth Sahayata's user avatar
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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/...
佐武五郎's user avatar
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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 $O$....
ebenezer's user avatar
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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 ...
Jos Bergervoet's user avatar
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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 ...
Zorua Chan's user avatar
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How do particle acquire thermal distribution?

Consider some toy N-body simulation: we start with a bunch of particles, discretize time, and simulate their interactions at each timestep. What numerical features should the simulation include to ...
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On beam suspended by wires

My question involves sample problem 9-8 of the book "Physics" by Halliday, Resnick and Krane, 5th edition. So I could understand the answer given but there is something that is not ...
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Gravitational Null Points in a system of point masses

For an equilateral triangle formed by 3 point masses which has a circumradius 'a' there are 4 null points: The centroid and 3 other points on the angular bisectors of the three sides. On calculation ...
Savith Rāllapallí's user avatar
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Is a body in uniform circular motion in equilibrium?

I know this question has been asked a myriad different times, but nowhere can I seem to find a definitive, final resolution to it. Is a body in uniform circular motion in equilibrium?
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Regarding the relation between statistical equilibrium and thermal equilibrium

I've seen a similar set of questions on the topic in SE but none seem to satisfy me.So,the question is as follows:1)What is the relation between thermodynamic equilibrium and statistical equilibrium ...
Arjun's user avatar
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Chemical equilibrium for distinguishable reactant particles

Denote the partition function of a single particle by $\zeta$. The particles of one type of reactant in a chemical reaction are normally indistinguishable. The partition function of $n$ number of a ...
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Direction of the normal force [closed]

Suppose we have a bar with non-zero mass inside a hemispherical bucket fixed to the ground. Suppose, too, that there is friction between the bar and the inner spherical surface of the bucket. Part of ...
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When calculating Lagrange points, $L_3$, $L_4$ and $L_5$ are good, but why are my $L_1$ and $L_2$ too close to the Earth?

I'm using python to calculate the Lagrange points of the Sun-Earth system. I started assuming that - for $L_1$ at least - the sum of the gravitational acceleration towards the Sun and the centripetal ...
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Is bouncing ball (100% collision) an oscillatory motion/SHM or both or none?

My teacher told me bouncing ball (100% elastic) is oscillatory motion that does not have a stable equilibrium position and restoring force. It is just to and fro motion and thus called oscillatory ...
Krishna Sharma's user avatar
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How to calculate equilibrium time for a communicating vessel with height difference?

The scenario is that a communicating vessel or a U tube without lids is filled with water. There is a height difference between the two pipes of this tube. Then there will be hydraulic pressure and ...
ooo's user avatar
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Can a body be in thermal equilibrium at a different temperature from surroundings?

As per my knowledge bodies attain constant temperature (thermal equilibrium with surroundings) when they absorb and emit energy at equal rates. Let us say temperature of surroundings is T1. We have a ...
ssr's user avatar
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How are curved soap films stable?

How do curved soap films remain in equilibrium, if surface tension tries to pull them taut? What I understand: Surface tension acts tangentially on a surface. The potential is energy is proportional ...
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Whether there is an isolated system, it will enter equilibrium [duplicate]

For a thermodynamically isolated system, will it eventually move toward thermal equilibrium? Will there be exceptions to the system?
zhou's user avatar
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Entropy variables

When we are defining the entropy we have been used two isolated system not a heat bath with a small system, to ensure that entropy is defined as an energy variable dependent. My question why is the ...
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The application of a minimum and maximum force

There are three blocks - a big block (C) above a horizontal surface that is smooth. A block (A) of mass m is resting on block C, and is also connected to another block (B) of mass m through an ideal ...
Shreya Murasing's user avatar
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A case of limiting equilibrium

I have noticed in the solutions of the problems of Friction of a physics book I'm studying from that in cases of limiting equilibrium, the force of friction $f$ to be equal to the coefficient of ...
Shreya Murasing's user avatar
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Mechanical Equilibrium and Zeroth Law of Thermodynamics

While reading Kardar's 'Statistical Physics of Particles', in section explaining Zeroth law of Thermodynamics, Kardar claims that each of the system's i.e A & B , B & C are assumed to be ...
Suhas Adiga's user avatar
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Reversible processes in thermodynamics [closed]

These are a few basic questions of mine in thermodynamics whose answer I can't find anywhere. $1$. How does a quasi static process serve the purpose of thermodynamic equilibrium?A quasi static process ...
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Static equilibrium of linkage [closed]

I have a question regarding the calculation of the forces of a linkage in static equilibrium. Consider the mechanism in the figure. Points A and B can move in all 3 directions (hence they have 3 DoFs ...
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Container divided by adiabatic wall with mass and friction: why is it a quasi-static process?

Thanks to the help of @ChetMiller, the following fact is essentially concluded in this thread. Consider a rigid, thermally isolated container divided by a massless barrier parallel to its base into ...
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Why equilibrium and not steady state?

Equilibrium and steady state are often misunderstood. Equilibrium: properties are uniform throughout and they do not vary with time. Steady State: properties at specific location do not vary with time....
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Container divided by frictionless adiabatic wall: reversible or irreversible process?

I have encountered an issue in the following physical situation. Consider a rigid, thermally insulated container divided by a barrier parallel to its base into two parts, left and right, each ...
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Is a body rotating in equilibrium? [duplicate]

If a body is performing a uniform rotation, do we consider it to be in equilibrium because of its constant speed? Or not because it has the centripetal force acting upon it so the sum of all forces is ...
Nick The Greek's user avatar
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Entropy and uncertainty principle

I know that entropy depends on the total energy of a system. In the energy-time uncertainty, howeve, energy can be uncertain for an amount of time which is related to the uncertainty of energy by ...
Ahmed Samir's user avatar
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1 answer
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Zeroth Law of Thermodynamics on Thermometer

I'm confused by how thermometer works based on The Zeroth Law of Thermodynamics. The Zeroth Law of Thermodynamics said that "If a body, A, be in thermal equilibrium with two other bodies, B and ...
aki's user avatar
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Determining melting point with equilibrium

A well known problem in thermodynamics is the determination of boiling points from the Van’t Hoff equation using the liquid-vapor phase equilibrium. When taking the temperature dependence of the ...
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Can a body be in both static and dynamic equilibrium simultaneously?

I was just studying statics when I realized that a body can be in both static or dynamic equilibrium at the same time but I am not so sure. My textbook says that an object at rest is in static ...
Spluesh's user avatar
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Rotational Equilibrium With Forces acting on only two points

Imagine a rod that is held at angle to the vertical by some hook. The rod is in equilibrium. There would be three forces on this rod - Normal contact, Friction, and the weight of the rod. I struggle ...
john's user avatar
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Work obtained during isentropic expansion in the Carnot cycle versus the work done to gradually lower the outside pressure

We have a Carnot cycle and lets say it is in thermal and mechanical equilibrium with the surroundings before the beginning of the process. I am using the convention that heat brought to the system is ...
User198's user avatar
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Contradicting Basic and Force definitions of types of Equilibrium

This question is neither a check my work question and nor a homework question, it is a conceptual doubt in a question I found and I have attached a solution just for reference to show how I drew my ...
Ham Lemon's user avatar
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Identification of Stable, Unstable, Neutral Equilibrium

Definition of Stable Equilibrium - When a particle is displaced infinitesimally, it returns back to the mean position and starts oscillating about it. Unstable Equilibrium - When a particle is ...
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Equilibrium in all directions

Let's say the origin is an equilibrium position for a particle. If we have a case such that a slight displacement of the particle in x direction makes it return to the mean position (stable ...
Ham Lemon's user avatar
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Definition of Stable, Unstable and Neutral Equilibrium using Force

So I have read that a particle is in Stable Equilibrium when the potential energy is minimum, Unstable Equilibrium when the potential energy is maximum and Neutral Equilibrium when the potential ...
Ham Lemon's user avatar
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How would a heat engine with 3 bodies work?

Say we have 3 equal bodies in contact, and there is a heat engine that absorbs and emits heat to these 3 bodies and it does work to an external medium. How would that work? I imagine that it would get ...
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If two bodies are completely insulated from each other and are at the same temperature, Are they said to be in thermal equilibrium with each other?

I have read, "Two bodies are said to be in thermal equilibrium if there is no net flow of heat from one to another" And also, "Heat is the form of energy transferred between two systems ...
Vibhusha's user avatar
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Show that equal pressure is the maximum entropy state

Some introduction and background Consider a thermally insulated reservoir filled with some gas. The reservoir is divided in two by a fixed, thermally conducting wall. Initially, the first compartment ...
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