Equilibrium Definition and 1000 Threads

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.

View More On Wikipedia.org
Recent contents Top users
  1. N

    Static equilibrium force decomposition problem

    If you see the $\sum \tau_0 = L\cdot N_1 \cdot cos \theta - LF_1 sin \theta - L/2 \cdot G cos \theta$, all the trigonemetric parts are all opposite of what i can understand, given the angle as drawed in the Picture/url. Please help me :)https://pasteboard.co/IiXr8qA.png
  2. Lone Wolf

    Static equilibrium -- interpretation of forces

    I solved this question correctly, however I have a question regarding how I should work with the weight of the firefighter climbing the ladder. When drawing the force diagram for this problem, I should only include forces acting on the ladder, right? Which means I would represent the normal...
  3. D

    Rigid body equilibrium question

    Problem in the picture. I have a question regarding the problem in the picture. Ma=0 -2Kn*1a+By*4a=0 --> By=0,5kN Mb=0 2kN*3a-Ay*4a=0 --> Ay = 1,5kN Ax=0kN Ay is the pin support and By is the roller support. According to the solution By should be 1kN but isn't that the wrong answer? 2kN has...
  4. D

    Why Is My Rigid Body Equilibrium Equation Incorrect?

    Hello Ihave gotten as far as coming up with an equation for the sum of moments and it goes as follows: bh*1/2b-1/2hb*1/3b=0 the answer for h i get is wrong and i don't know if i am missing something. moment arm on the b is 1/2b and the moment arm on h is 1/3h because of the way water pressure...
  5. cianfa72

    Daniell cell initial equilibrium

    Hello, consider again a simple Daniell cell with salt bridge in place but no external electric connection between electrodes. Reading from some source e.g. link1 it seems upon Zinc and Copper metal rods are dipped into their own ions solution, both will gain a negative charge (-) due to an...
  6. J

    Find the equilibrium temperature & the amount of ice/water

    That's how far I've gotten and now I'm stuck!
  7. M

    Asymmetrical Static Equilibrium

    a) Answer that I found: 56.31 degrees b) Answer that I found: 121.71 Kg For b) not sure if I need to add the 20 N and 5 N to the total of the cargo mass.
  8. D

    Find the tensions of two strings in mechanical equilibrium

    I tried to do the free body diagram of the problem, but I{m confused because the rule is inclined. Should I just use the given angles to calculate the forces on x and y? Also, how should I calculate the torques? Since I don't know the dimensions of the rule. Can you help me? I think that once I...
  9. Alif Yasa

    Find the equilibrium angle of this unusual driven pendulum geometry

    -I tried to draw the forces on the hoop when it is in the equilibrium state. I know there are friction and normal force on the contact point of the shaft and the hoop -I also put the weight force to the M object -But when i used the torque equilibrium, where the pivot is the contact point of the...
  10. D

    A position of stable equilibrium, and the period of small oscillations

    I tried by taking the derivative of the potential to find the critic points and the I took the second derivative to find which of those points are minimum points. I found that the point is ##x=- a##. I don't understand how to calculate the period, since I haven't seen anything about the harmonic...
  11. QuasarBoy543298

    The zeroth law of thermodynamics

    let's assume I have 2 systems A and B. the surface that describes when the 2 systems are in equilibrium is given by F(a1,a1,...,b1,b2,...) = 0. assuming we can write this surface as A(a1,a2,..)=B(b1,b2,...) why do A and B describes the temperature function of the systems? in class, we...
  12. Np14

    What is the tension force for this system in rotational equilibrium?

    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...
  13. 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...
  14. A

    Mass hanging from a 2-pulley system

    Homework Statement I have a question about the pulley problem in the attachment. Homework Equations This question can be answered using equilibrium of forces, namely Fx = 0 and Fy = 0. The Attempt at a Solution The answer key states that for the sum of the x-components, we should use the...
  15. mmest

    Magnetic Field required to hold a loop in static equilibrium

    Homework Statement There is a square loop with mass of 4.0 kg and side length 4.5 m that is tilted upwards from the ground at a 25 degree angle with one side resting on the surface. The loop is a conductor that has 25 A of current going through it. The question asks to find the strength a...
  16. Romain Nzebele

    Understanding Free Body Diagrams: Explaining the Forces on a Compressed Board

    Hello everyone. I find the following problem confusing. A board sandwiched between two boards in the figure below weighs 95.5N. If friction exists between the middle and the compressing boards, draw the free body diagram of the middle board. Below I attached the diagram found in the solution...
  17. S

    Equilibrium problem with 5 unknowns

    Homework Statement This is an equilibrium problem with 3 unknown forces, and 2 unknown angles. I have resolved the horizontal and vertical forces. Homework Equations Horizontal components of forces: -W1cos Θ + W3cos ∅ = 0 Vertical components: W1sin Θ + W3sin ∅ - W2 = 0 Where W1, W2, W3...
  18. M

    Chemistry Equilibrium Partial Pressures

    Homework Statement Kc = 4.15 x 10-2 at 356°C for PCl5(g) ↔ PCl3(g) + Cl2(g). A closed 2.00 L vessel initially contians 0.100 mol PCl5. Calculate the total pressure in the vessel (in atm to 2 decimal places) at 356°C when equilibrium is achieved. Homework Equations PV=nRT Kp= Kc(RT)^change in...
  19. W

    Thermal Physics: Interpretation of equilibrium constant

    For a reaction defined as such, $$A\rightleftharpoons B$$ the equilibrium constant ##K## is defined by ##K = p_B / p_A##, with ##p## denoting the partial pressure (edit: at equilibrium). However, if ##K<<1##, which implies ##p_A >> p_B##, it is said that the backwards reaction dominates and that...
  20. M

    Kc = 1.88 for 2HI(g) ↔ H2(g) + I2(g)

    Homework Statement Kc = 1.37 for HI(g) ↔ 1/2 H2(g) + 1/2 I2(g). What is Kc (to 3 decimal places) for H2(g) + I2(g) ↔ 2HI(g)? Homework Equations Kc= Products/Reactants, Ice Tables The Attempt at a Solution I tried an ice table, but I’m not sure what to do with the Kc value I’m given when I...
  21. H

    Question about a system in thermodynamic equilibrium

    What are the precise conditions for thermodynamic equilibrium? I know that a system in thermodynamic equilibrium must have constant temperature and that there can be no net macroscopic flow of energy or matter. However, is it possible for there to be a system in equilibrium that has a spatially...
  22. S

    Static equilibrium -- A picture hanging on a wall

    Homework Statement https://imgur.com/v13K6sE a uniform rod of mass m is placed as shown, with one of its end resting on a smooth wall while 1/4 of the rod's length is sticking out of a rough table. Find the net force the table exert on the rod at the corner. Homework Equations i drew the free...
  23. J

    The concentration of B at equilibrium

    Homework Statement For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00L container. A(g) + 2B(g) --> C(g) At equilibrium, the concentration of A is 0.246 mol/L. What is the concentration of B at equilibrium? Homework Equations for aA+bB-->cC, K = [C]^c/([A]^a[...
  24. 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...
  25. D

    Equilibrium : normal reaction of a rotational center?

    Homework Statement I'm trying to figure out the reaction at D,that's where the system can rotate. Problem: A force P of magnitude 90 N is applied to member ACDE, which is supported by a frictionless pin at D and by the cable ABE. Since the cable passes over a small pulley at B, the tension...
  26. karush

    MHB -s1.2.4 Find the equilibrium solution y_e

    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...
  27. Chromatic_Universe

    A Equilibrium recombination temperature for Helium

    How to get to the expression for equilibrium recombination temperature for Helium?
  28. Y

    I Definition of 'dynamical equilibrium'?

    "Assuming that the system is in dynamical equilibrium – that the magnitude of the total potential energy is equal to twice the kinetic energy – a so-called “dynamical mass” can be derived..." https://astrobites.org/2012/03/16/what-defines-a-galaxy/ I am trying to understand what is meant by...
  29. Raihan amin

    Equilibrium height of an air parcel

    Homework Statement An air parcel is investigated to study the weather.It rises up and rests at an equilibrium height in the atmosphere,where its weight is exactly balanced by the upward buoyant force. We shall assume ideal gas law to hold for all processes and neglect the mass of the air...
  30. M

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

    Homework Statement A mass of 3kg is acted upon by three forces of 4.0 N, 6.0N, and 9.0N and is in equilibrium. The 9N force is suddenly removed. Determine the acceleration of the mass. Homework Equations F=ma. The Attempt at a Solution My main problem with this question is that I cannot think...
  31. thebosonbreaker

    Resolving forces: Mass on a string

    Homework Statement A mass of 50 grams hangs in equilibrium on a string. The mass is pulled aside and upwards by a force of 0.3N which makes an angle of 30° with the horizontal. Find the angle that the string makes with the vertical and the tension in the string. Homework Equations Body is in...
  32. Arman777

    Spring static equilibrium Problem

    Homework Statement a) If the distances ##s_1## and ##s_2## are the amounts the springs are streched while in static equilibirum, Write down the static equilibirum equations. b) When the system is distrubed from its equilibirum state, both mases move vertically. Let ##y_1(t)## and ##y_2(t)##...
  33. Dave1212

    Calculating equilibrium constants Keq

    Homework Statement 2Fe(s) + 3Cl2(g) ⇔ 2FeCl3(s)[/B] Keq = 53.25 [CL2(g)] = ?M Answer = [0.2658M] Homework Equations Keq = (cC)(dD)/(aA)(bB) The Attempt at a Solution Keq = [Cl2]3 53.25 = (Cl2)3 I’m confused because I feel like I need more to work with in this question. It seems like I...
  34. S

    Static equilibrium: Find the tension in a support cable

    Homework Statement Homework Equations Σtorque = 0 Σfx=0 Σfy=0 torque= F r sinθ (θ is the angle between the r and the F)The Attempt at a Solution OKay, now i know how to solve this, but it's like i asked myself, how to know if this is a question that i am supposed to use Σfx=0 and Σfy=0...
  35. F

    Statics and equilibrium - asking for some guidance

    Hi, I'm not used to communicate physics in English, so my language may be a bit off. This task is fairly simplistic. It's a figure which is held up in points A and B (both having an x and y force exerted on them), and the figure has a joint C. It is depicted in attached files. The answers...
  36. Cocoleia

    Finding nearest neighbour equilibrium distance

    Homework Statement The energy per ion in for CsCl is nearly – (αe 2 /(4πε0)) + 8Ae -(R/ρ) , where α is the Madelung constant and A = 5.64 x 103 eV and ρ = 0.34 Å. Calculate the nearest neighbour equilibrium distance. Homework Equations alpha = 2 ln 2 The Attempt at a Solution I think that...
  37. S

    Can Twine Support a 15-N Picture Without Breaking?

    Homework Statement you want to hang a 15-N picture as in part (a) using some very fine twine that will break with more than 12 N of tension can you do this? what if you have it as illustrated in part (b) of the figure? Homework Equations Σf=ma The Attempt at a Solution [/B] okay i started...
  38. patrykh18

    Energy of a crystal in thermal equilibrium

    Homework Statement In a monatomic crystalline solid each atom can occupy either a regular lattice site or an interstitial site. The energy of an atom at an interstitial site exceeds the energy of an atom at a lattice site by an amount ε. Assume that the number of interstitial sites equals the...
  39. 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...
  40. 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...
  41. 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...
  42. prashantakerkar

    B Is Equilibrium a Scalar or Vector Quantity?

    1 Is Equilibrium a Scalar or Vector quantity? 2 What is the unit of Equilibrium? Thanks & Regards, Prashant S Akerkar
  43. SchroedingersLion

    I Statistical Physics - Equilibrium

    Good evening, I have a question to a short introduction to statistical mechanics in a book about molecular dynamics simulation. It introduces the fundamental assumption: Every microscopic state with a fix total energy E is equally probable. I attached the section. I understand it all, except...
  44. evinda

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

    Hello! (Wave) I want to find the equilibrium solutions and determine their stability. $(1)\left\{\begin{matrix} \dot{x}=-y-x(1-\sqrt{x^2+y^2})^2\\ \dot{y}=x-y(1-\sqrt{x^2+y^2})^2 \end{matrix}\right.$ I also want to check the behavior of the solutions of $(1)$ when $t \to \infty$. There are...
  45. A

    Finding where an electron would be in equilibrium

    Homework Statement A point charge of -1.0 µC is located at the origin. A second point charge of 16 µC is at x = 1 m, y = 0.5 m. Find the x and y coordinates of the position at which an electron would be in equilibrium. Homework Equations F=k((q1q2)/r^2) The Attempt at a Solution I have gotten...
  46. Physicsterian

    Defining equilibrium and movement in pulley arrangements

    Homework Statement I had to answer which of the pulley arrangements illustrated (see picture) is in equilibrium (the drawing went a bit difficult, please see all outer boxes as equal in size and the middle ones as well) I managed to answer that it is arrangement C, by finding out that...
  47. 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
  48. QuarkDecay

    How to Prove P+B²/8π in MHD Equilibrium?

    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...
  49. Beth N

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

    Homework Statement Two uniform 150 N rafters rest on frictionless floor, held together by a rope. A 500 N load is held at their apex. Find tension in the tie rope. Homework Equations ##torque= rFsin \theta =Force*Moment Arm ## The Attempt at a Solution The angle ##\theta## in the picture...
  50. 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...
Back
Top