What is Equilibrium: Definition and 1000 Discussions

Thermodynamic equilibrium is an axiomatic concept of thermodynamics. It is an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermodynamic equilibrium there are no net macroscopic flows of matter or of energy, either within a system or between systems.
In a system that is in its own state of internal thermodynamic equilibrium, no macroscopic change occurs.
Systems in mutual thermodynamic equilibrium are simultaneously in mutual thermal, mechanical, chemical, and radiative equilibria. Systems can be in one kind of mutual equilibrium, though not in others. In thermodynamic equilibrium, all kinds of equilibrium hold at once and indefinitely, until disturbed by a thermodynamic operation. In a macroscopic equilibrium, perfectly or almost perfectly balanced microscopic exchanges occur; this is the physical explanation of the notion of macroscopic equilibrium.
A thermodynamic system in a state of internal thermodynamic equilibrium has a spatially uniform temperature. Its intensive properties, other than temperature, may be driven to spatial inhomogeneity by an unchanging long-range force field imposed on it by its surroundings.
In systems that are at a state of non-equilibrium there are, by contrast, net flows of matter or energy. If such changes can be triggered to occur in a system in which they are not already occurring, the system is said to be in a meta-stable equilibrium.
Though not a widely named "law," it is an axiom of thermodynamics that there exist states of thermodynamic equilibrium. The second law of thermodynamics states that when a body of material starts from an equilibrium state, in which, portions of it are held at different states by more or less permeable or impermeable partitions, and a thermodynamic operation removes or makes the partitions more permeable and it is isolated, then it spontaneously reaches its own, new state of internal thermodynamic equilibrium, and this is accompanied by an increase in the sum of the entropies of the portions.

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  1. QuasarBoy543298

    The zeroth law of thermodynamics

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  2. Np14

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    The system is in rotational equilibrium and therefore experiences no net torque, meaning all individual torques must add to zero. τNET = 0 = FFTsin(θ)L - FgL - Fg(L/2) τNET = 0 = FTsin30°(0.6?) - (0.5)(9.8)(0.6) - (2.0)(0.6/2) My only problem (I think) is figuring out what the length L is for...
  3. R

    How many times per minute does an object pass equilibrium? (Diff Eqs)

    Essentially, my question boils down to just part b. My initial thoughts on how to solve this are illustrated above in the second image. To me, I had just interpreted omega, the frequency, as cycles per second. From there, I simply multiplied to get it into minutes. After discussing with a prof...
  4. A

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  5. mmest

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  6. Romain Nzebele

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  7. S

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  8. M

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  9. W

    Thermal Physics: Interpretation of equilibrium constant

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  10. M

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  11. H

    Question about a system in thermodynamic equilibrium

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  12. S

    Static equilibrium -- A picture hanging on a wall

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  13. J

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  14. bardia sepehrnia

    Statics problem (moment and equilibrium)

    1. Having really hard time understanding the concept of moment and equilibrium in statics. In the following picture the man is carrying a 6kg uniform rigid board. I'm asked to calculate the amount of force the man feels on his shoulder. (at point A) Now I know I'm supposed to start by making...
  15. D

    Equilibrium : normal reaction of a rotational center?

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  16. karush

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    1000 $\textsf{Consider the differential equation $\displaystyle \frac{dy}{dt}=ay-b$}$ (a) Find the equilibrium solution $y_e$ rewrite as $y'-ay=b$ $\displaystyle -\exp\int a \, da=e^{a^{2}/2}$ $\color{red}{y_e=b/a}$ (b) Let $Y(t)=y-y_e$; thus $Y(t)$ is the deviation from the equilibrium...
  17. Chromatic_Universe

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  18. Y

    I Definition of 'dynamical equilibrium'?

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  19. Raihan amin

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  20. M

    Can 3 forces of 9N, 4N, and 6N be in equilibrium?

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  21. thebosonbreaker

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  22. Arman777

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  23. Dave1212

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  24. S

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  25. F

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  26. Cocoleia

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  27. S

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  28. patrykh18

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  29. harambe

    Calculating concenteration at equilibrium

    Homework Statement 0.1mole of N2O4 (g) was sealed In a tube under one atmospheric conditions at 25°C.Calculate the number of moles of NO2(g) present if the equilibrium N204(g) --->2NO2(g) (Kp=0.14) is reached after some time Homework Equations K=[NO2]^2/[N2O4] 3. The attempt...
  30. harambe

    Equilibrium Constant for Alcohol and Acetic Acid Reaction at 25°C | Homework

    Homework Statement One mole of pure ethyl alcohol was treated with one mol of pure acetic acid at 25 °C.One third of acid changes into ester at equilibrium The equilibrium constant for the reaction will be Homework Equations C2H5OH+CH3COOH------>C2H5COOCH3[/B] K={A}^m{B}n/{C}^x{D}^z where...
  31. Frankenstein19

    Equilibrium distribution of a solvent in two immiscible solvents

    Homework Statement I need to find the distribution coefficients for acetic acid of various concentrations in a ether/water system, but I'm not too sure of my calculations Homework Equations To get the concentrations of acetic acid in the aqueous phase I took the ([average concentration of...
  32. prashantakerkar

    B Equilibrium - Scalar or Vector?

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  33. SchroedingersLion

    I Statistical Physics - Equilibrium

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  34. evinda

    MHB Finding Equilibrium Solutions & Stability of $(1)$

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  35. A

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  36. Physicsterian

    Defining equilibrium and movement in pulley arrangements

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  37. S

    B Maximum Overhang in Static Equilibrium

    Hi, i am trying to trying to solve this question as this question is slightly different from the usual type of overhanging question. Please advice on the approach. Thank you I have to find the maximum overhang possible, l, before the whole blocks falls apart
  38. QuarkDecay

    MHD Equilibrium: Prove P+B2/8π

    Homework Statement Prove that in an MHD equilibrium state in a pinch with flux and Bθ(r) and Bz(r), the equation for pressure is; d/dr(P + B2/8π) + Bθ2/4πr - ρ( u2θ/r)= 0 B is the total Magnetic field, uθ(r) the velocity of plasma, ρ= density, and solving in a (r,θ,z) system Homework...
  39. Beth N

    Equilibrium of Rigid Bodies. Rafter. What is moment arm?

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  40. W

    My Second Post: Change in Magnitude of Normal Force?

    Hello, Let us imagine a solid immersed in a liquid in a container such that the density of the liquid is less than the density of the solid. This means that the solid must sink. Let us study the solid when it reaches the bottom surface and is now at rest. The forces acting on the solid when it...
  41. Mason Smith

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  42. Andres Padilla

    FBD of an aerogenerator (Windmill)

    Homework Statement Good afternoon, I hope someone could help me with this problem, it is killing my head. I have an aerogenerator, I already find the torque excerted by the air (75.8N) and the force transmitted by the gear (1010.6N). The problem comes when I try to draw the free body diagram to...
  43. A

    Quick clamp wedge/friction lock calculation

    I am currently working on designing a linear brake/lock for a completely different purpose but it will be based on the same principle as in a quick clamp shown below. Before building a prototype I do want to make some rough calculations to check dimensions, angles etc. etc. However, I am for...
  44. C

    I Activity of daugther isotope in secular equilibrium

    Consider chain of two radioactive decays ##A \to B\to C##. The equation that regulates ##N_B## is $${\frac {\mathrm {d} N_{B}}{\mathrm {d} t}}=-\lambda _{B}N_{B}+\lambda _{A}N_{A}$$ I can't understand why the activity of ##B## is get as ##\lambda_B N_B##, for example at page 20 here...
  45. S

    Chemical equilibrium vs pressure

    Homework Statement Consider the reaction : A⇔2B (⇔ stands for reversible). 1 mol of A and 2 mol of B are taken in a closed container at equilibrium. Suppose the pressure is increased, how much of B (by moles) will decompose to restore equilibrium ? Homework EquationsThe Attempt at a Solution...
  46. A

    Finding Equilibrium in Electric Fields of Two Charges

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  47. P

    Thermal equilibrium in open systems

    Is it possible for an open system to reach thermal equilibrium? why/why not?
  48. Z

    Equilibrium: Le Chatelier's Principle and CaCO3 Decomposition

    Homework Statement I had a question on a test and I got the wrong answer, but I still don't understand why. It was a Le Chatelier problem about the equilibrium shift, and it described the decomposition of CaCO3 CaCO3(s) <->CaO(s) + CO2(g) The question asked something along the lines of "If...
  49. J

    For a solution that contains 0.10 M HCN and 0.10 M NaCN, whi

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  50. thevinciz

    Equilibrium of a stiff plate on inclined planes

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