What is Reversible: Definition and 247 Discussions

Reversible computing is a model of computation where the computational process to some extent is time-reversible. In a model of computation that uses deterministic transitions from one state of the abstract machine to another, a necessary condition for reversibility is that the relation of the mapping from states to their successors must be one-to-one. Reversible computing is a form of unconventional computing.
Due to the unitarity of quantum mechanics, quantum circuits are usually reversible.

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  1. A

    Reversible engines with different efficiencies

    Is is possible to have 2 different engines with all the following criterion? 1) Are reversible 2) Work differently (different cycles) 3) At the same working temepratures have different efficiencies. E.g. Working temperatures 100K and 50K. Engine 1: Carnot's Efficiency - 50%...
  2. J

    Q) Reversible and Irreversible processes

    I am studying Reif's Fundamental of Statistical and Thermal Physics. (p.91) he explain about Reversible and Irreversible processes by using "The number of accessible states in equilibrium(Ω)". in his point of view, each accessible states have equal probability. comparing to weather...
  3. O

    Curie temperature, reversible process

    Hello guys, first post in this forum :) Magnetism has always been complicated to understand for me, and I would like some help regarding Curie temperatures. We have just bought a new measurement equipment to out lab which shall be temperature calibrated with curiepoints. We have three...
  4. S

    Is the Biot-Savart Law reversible?

    Please find the attachment and comment about equation (2).
  5. Soumalya

    Understanding reversible and irreversible process

    Hello, It is said that any process accompanied by dissipating effects is an irreversible process.For instance, a piston cylinder arrangement undergoing an expansion of a gas with heat lost as friction between surfaces is an irreversible process.Here the system does work on the...
  6. P

    How to tell the difference between reversible and irreversible process

    Imagine a rigid block of steel at 100 degrees celsius which is inserted into water at 0 degrees celsius. They then both get an equilibrium temperature. How can I tell whether this is a reversible or irreversible process? What is the argumentation?
  7. Feodalherren

    Thermodynamics - reversible isothermal cycle

    Homework Statement Homework Equations The Attempt at a Solution I can do everything else except work for part one going from A to B. What I did was -∫PdV = -nRT ∫(1/v)dV = -nRT ln (Vf/Vi) I can solve for T because everything is given, T in Kelvin is 882. From PV=nRT T=(5atm)(10L)/1mol*R...
  8. G

    Reversible Clapeyron cycle efficiency

    Homework Statement The Clapeyron cycle efficiency is similar to the Carnot cycle except that two adiabatic paths are replaced with isobaric processes a) based on the above information, draw a Clapeyron cycle. b)Derive the efficiency of the reversible Clapeyron cycle Homework...
  9. N

    Thermodynamics: Why must a reversible process be infenetesimally done?

    So my professor keeps bringing up that a reversible process must always be done infinitesimally slowly up. But why is that? I can't recall the explanation.
  10. Z

    Entropy for Reversible and Irreversible Processes

    Hello everyone, I've been reviewing some concepts on Thermodynamics and, even though I feel like I am gaining a level of comprehension about the subject that I could not have achieved before as an undergraduate, I am also running into some situations in which some thermodynamic concepts seem to...
  11. M

    Reversible Processes: Quasi-Static Adiabatic Expansion from Callen Ch. 4

    I'm working from Callen ch. 4: Consider a monatomic ideal gas in a cylinder fitted with a piston.The walls of the cylinder and the piston are adiabatic. The system is initially in equilibrium, but the external pressure is slowly decreased. The energy change of the gas in the resultant...
  12. B

    Solve Mystery of qrev & ΔS for Reversible Heat Gain

    I know that ΔS=qrev/T for any process, but what is qrev here? It can't be identical to the q in ΔU=q+w - if it was, why don't we just write it q? The other problem is that it would mean that ΔS(surroundings)=-ΔS(system) which need not always be true. Secondly I want to derive the equation for...
  13. binbagsss

    Thermodynamics, Entropy, Clausis Inequality, Reversible and Irreversib

    ∫dQ/T≤∫dQ(rev)/T * , where both integrals are evaluated between the same thermodynamic coordinates- A and B , say. - I am having trouble interpreting this inequality. -( I understand the derivation in my textbook via the Clausius diagram(considering a reversible and an ireversible process...
  14. U

    Reversible cycles and entropy generation

    I've got a couple of questions about reversible cycles: So if we have two gaseous systems and have a reversible cycle working between them, then the entropy generation within each gaseous system is zero, right? Do turbines execute reversible cycles? Thanks a lot for your help!
  15. S

    C(v,m) vs C(p,m) and adiabatic, reversible work

    Homework Statement A sample of carbon dioxide, mass 2.45g, is allowed to expand reversible & adiabaticly from 500cm3 to 3.00 dm3 What is the work done by the gas Homework Equations dw=-pexdV du=dq+dw du=nCv,mdt The Attempt at a Solution At first i just wanted to say that because...
  16. S

    Reversible and Irreversible reactions

    There are 2 types of reactions 1) Being fully irreversible and 2) reversible So for 1) the graph of Gibbs energy against the progress of reaction would look like this: http://postimg.org/image/phycri0vr/ So the difference between 100% product and 100% reactant is the ΔG of the reaction...
  17. S

    Reversible heat pump - Work input?

    1. An ideal heat engine (HE) is used to drive a reversible heat pump (HP) as shown in figure below. The HE takes in Q1 heat units at T1 and rejects Q2 at T2. The HP abstracts Q4 from the sink at T4 and discharges Q3 at T3. Develop an expression for the ratio Q4/Q1 in terms of...
  18. naima

    May decoherence be reversible?

    I found an interesting paper here a two level system is measured by a harmonic oscillator(the apparatus). the apparatus is coupled to its environment, a bath of oscillators. The article shows how the reduced matrix of S+ A decoheres (the off diagonal elements tend to zero). I am looking for a...
  19. S

    Prove that A is reversible matrix if B is reversible

    Using A\widetilde{A}=(detA)I prove that \widetilde{A} is reversible matrix if and only if A is reversible. Also prove det(\widetilde{A})=(detA)^{n-1} for any square matrix A. First part: 1. direction: Lets say \widetilde{A} is reversible, this means that \widetilde{A}\widetilde{A}^{-1}=I...
  20. ShayanJ

    The importance of reversible processes(?)

    In thermodynamics(at least in classical thermodynamics),the idealization of reversible processes is used time and again.Can we say it is central to thermodynamics? I mean can we say it is so important that if we can't find a reversible counterpart for an irreversible process,then the existence...
  21. J

    Do all reversible engines become heat pumps?

    I have a cycle (and the gas is ideal) that starts at Pressure=4Po Volume=Vo and and Temperature=Th. First step it's cooled at constant volume to Tc and Po; Second step, it is reheated at constant pressure to Th and 4Vo, and lastly it is compressed at constant temperature to Vo and 4Po. For those...
  22. I

    Is radioactive decay reversible in time?

    I ask this because I've heard repeatedly that all the equations in current physics models are reversible in time, save the second law of thermodynamics. But does this mean the process of radioactive decay is also reversible in time?
  23. F

    Reversible, Isothermal Compression from P1 to P2. How much heat?

    ∫Homework Statement Compress a body reversibly and isothermally from P1 to P2. How much heat goes in or out?Homework Equations Maxwells four relations, differential forms of the four thermodynamic potentials (Central, Enthalpy, Gibbs, Helmholtz) The Attempt at a Solution My problem is that...
  24. A

    Don't reversible processes always do the most possible work?

    I am trying to teach myself the basics of thermodynamics using a book I bought from a university book store. My question relates to the amount of work done by reversible vs irreversible processes. An example in the book (Chemical Principles by Atkins & Jones) reads the following: "A cylinder...
  25. tsuwal

    Thermodynamics: Is Stirling engine reversible or irreversible?

    Stirling engine: the cycle is composed by two isothermals and 2 isometrica and there are just two heat reservoirs. By the isometrics I would say that that it is irreversible since you exchanging heat with a reservoir at a different temperature than your gas. However my notes say the...
  26. H

    What is a reversible cyclic process?

    I know carnot's cycle is an example. but what is it exactly? a cycle in which ever part of process has a 'counter-process' please elaborate.
  27. N

    Thermodynamics reversible isothermal process

    Homework Statement A system containing 10kg of water undergoes a reversible isothermal process. The initial state can be characterized as saturated vapor at 300°C. The pressure in the final state is 1MPa. The heat transfer during the process in (inKJ) Homework Equations Q = m(U2-U1)+W...
  28. C

    Feynman's reversible lifting machine analogy- help

    Hi I'm having a very hard time trying to picture an argument in Feynmans physics volume one ). I can't picture this example he is talking about, so I wrote it down from the book and really hope someone can help me answer the question in the bottom. From the book (everything needed to know...
  29. B

    Heat in reversible isothermal expansions

    Heat is defined as "the transfer of energy owing to a temperature difference between two bodies". Consider a gas expanding against a massless frictionless piston. Assume that the process is both isothermal and reversible, and that the gas is ideal, so that its internal energy does not change...
  30. B

    Entropy change in a reversible adiabatic process

    For a reversible process, I imagine it is correct to say that dS = \frac{dq}{T} where all quantities refer to system quantities (not the surrounding). However, for an adiabatic process, dq = 0 . Thus, should it be the case that for an adiabatic reversible process, dS =...
  31. A

    (Thermo) Show that in a Reversible Adiabatic process

    Homework Statement Show that in a reversible adiabatic process, for 1 mole of ideal gas P1V1γ=P2V2γ Where, γ=CP/CVHomework Equations Listed above.The Attempt at a Solution Frankly, I don't really understand what I'm being asked to do.
  32. J

    Reversible Adiabatic Compression: Enthaply Calc

    Homework Statement a fluid undergoes a reversible adiabatic compression from .5 MPa, .2 m3 to .05 m3 according to the law PV1.3 = constant. determine the change in enthalpy, internal energy and work transfer during the process. Homework Equations P1V11.3 = P2V21.3 dH = T dS + V dP dS = 0...
  33. S

    Energy generation form heat using reversible equations

    Please don't be harsh on me. I just heard of reversible equation and had this thought: Is it possible to separate reactants from equilibrium and then later use it for energy generation? Kind of like water evaporating and absorbing heat energy.
  34. T

    Final temperature in reversible expansion

    Homework Statement One mole of an ideal monatomic gas initially at volume Vi and temperature 1000k expands to a final volume Cvi in three reversible steps: 1) isothermal expansion from Vi to aVi, 2) adiabatic expansion from aVi to bVi and 3) isothermal expansion from bVi to Cvi In terms...
  35. Y

    Equilibrium constants Ka, Kc, Kx, Kp and rate constants in reversible reactions

    Is the statement Ke=k+/k- valid for all equilibrium constants like Ka, Kx, Kp, Kc? All of the expressions I have found for this statement relate Kc, k+ and k- only.
  36. J

    Ligand Exchange - are they reversible?

    Are ALL ligand exchange reactions reversible? Therefore, if the Kstab of one complex is LESS than that of the other complex, would it ONLY be possible to form the LESS stable complex by 'flooding' the mixture with the appropriate ion. (these values are not real but they illustrate what I...
  37. R

    Showing work done on gas in a reversible process

    Homework Statement Ideal gas initially at temperature Ti, Pressure Pi, Volume Vi is compressed reversibly down to half its original volume. Temperature of gas is varied during the compression so that P = AV is always satisfied [where A is a constant] Show that the work done on the...
  38. A

    Obtaining gamma (γ) in an adiabatic, reversible expansion

    PROBLEM: One mole of an ideal monatomic gas initially at 300 K (T1) and a pressure of 15.0 atm (P1) expands to a final pressure of 1.00 atm (P2). The expansion occurs via an adiabatic and reversible path. Calculate q, w, ΔU, and ΔH. SOLUTION: q = 0 (adiabatic; no heat exchange occurs)...
  39. O

    [Thermodynamics] Calculate change in entropy of closed reversible system

    Homework Statement Mercury is a silvery liquid at room temperature. The freezing point is -38.9 degrees celcius at atmospheric pressure and the enthalpy change when the mercury metls is 2.29 kJ/mol. Wat is the entropy change of the mercury if 50.0 g of mercury freezes at these conditions? The...
  40. G

    Change in I.E. for a reversible process

    Homework Statement A system absorbs QH = 481 J of heat reversibly from a hot reservoir at temperature TH = 370 K, and gives off QC = 155.4 J of heat to a cold reservoir at TC = 156 K. During this process, W = 90.9 J of work is done by the system. a) Find ΔIE, the change in internal energy...
  41. K

    Reversible adiabatic expansion using Van der Waals' equation

    Homework Statement A real gas obeys Van der Waals‟ equation, which for one mole of gas is (p + A/V2)(V-B) = RT and its internal energy is given by U = CvT - A/V where the molar heat capacity at constant volume, Cv , is independent of the temperature and pressure. Show that the relation...
  42. M

    A closed system containing a gas is to undergo a reversible process

    Homework Statement A closed system containing a gas is to undergo a reversible process from an intial specific volume of 2 ft^3/lbm and a intial pressure of 100 psia. The final pressure is 500 psia. Compute the work done per unit mass. a. Pv= constant b. pv^-2 = constantHomework Equations (1)...
  43. S

    Inverse Maps: What Makes a Map Reversible?

    consider we have a map. what condition should have our map that it has inverse?
  44. M

    Analyzing a partially reversible cycle

    Thermodynamic: Analyzing a partially reversible cycle Homework Statement A cycle (which at first appears to be a Carnot cycle) consists of a reversible isothermal process (with reversible heat exchange with a reservoir at 500 C), followed by an adiabatic process, which is followed by...
  45. L

    Why must Quantum Computers be reversible?

    Although I've read many times that quantum computers are reversible, I am unable to find a understandable explanation as to why (this may be because I study Computer Science). From what I've read, I assume that the answer is linked to the Second Law of Thermodynamics, but I don't know how...
  46. T

    Justification of generalisation from reversible processes to all procesess

    Hi all, I've been having some difficulty understanding the derivation of the Fundamental Theorem of Thermodynamics, dU=T \ dS-P \ dV. The derivation, which can be found at Wikipedia (http://en.wikipedia.org/wiki/Fundamental_thermodynamic_relation) first starts with the universal First Law...
  47. Y

    Leeson Reversible Electric Motor - 1/3 HP, 1725 RPM

    hi .i am new here i like to know if this motor can't reversed using a switch from turning right to left . i am a knifes maker [was] and my motor have to turn clock wise and counter clock . thank you . yvesj
  48. M

    Reversible Carnot Cycle and Heat Engine

    Homework Statement A borehole produces 120kg/s of high pressure water at 165°C. A powerplant is to be designed to extract heat from the water, reducing the temp to 147°C. The plant which will initially be assumed to be reversible, will reject heat at 17°C to a river. Take 147°C as the highest...
  49. F

    Is electroweak symmetry breaking a reversible process?

    I can only assume it is, if a Higgs can be found anyway. I learned about hysteresis in certain physical processes. I don't have the math to guess nor Google skills to find a clear answer. If it were, would a sufficiently large and hot enough black hole be in danger of losing its mass terms...
  50. W

    The motor that drives a reversible refrigerator produced 142 W

    Homework Statement The motor that drives a reversible refrigerator produced 142 W of useful power. The hot and cold temperatures of the heat reservoirs are 20°C and -6.1°C. What is the maximum amount of ice that can produce in 2.2 hours from water that is initially at 6.0°C? Homework...
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