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.

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

    How Does Reversible Expansion Calculate Work in Thermodynamics?

    Homework Statement Okay i feel like I'm going crazy. Here is a sample problem my professor gave me. But I cannot figure out for my life how he got his answer and it hsould be very simple. A 10.0 mol sample of a perfect gas having Cv = 2.0R undergoes a reversible expanion form 5.00 L to...
  2. J

    Entropy related questions - Reversible or Irreversible?

    Entropy related questions -- Reversible or Irreversible? Homework Statement A 15.0kg block of ice at 0C melts to liquid water at 0C inside a large room that has a temperature of 20C. Treat the ice and the room as an isolated system, assume that the room is large enough for its temperature...
  3. N

    Prove non adiabatic reversible expansion and ΔS

    Homework Statement One mole of a monatomic ideal gas is transformed from 0.00°C and 2.00 atm to -40.0°C and 0.400 atm. Show that this is NOT an adiabatic reversible expansion and calculate ΔS for the change. (Hint: you will need to consider a reversible path that includes a...
  4. P

    Calculating Max Work from Reversible Cooling of Liquid

    Homework Statement One mole of a liquid with a constant molar heat capacity of 132 j/mol K is initially at a temp of 80 C. The heat capacity is independent of tempearture. Calculate the maximum work that could have been done onthe surroundings while cooling the liquid reversibly. The...
  5. N

    Ideal Gas Expansion: Reversible Process Calc.

    One mole of an ideal gas having CV = 25.0 J.K−1 is in a volume V1 = 28.0 L at P1 = 1.00 bar. It is expanded reversibly along a path given by P = P1 − 0.005000(V − V1) to a final volume V2 = 100.0 L. Calculate the final temperature T2 and the values of q, w, ΔE, ΔH for this change in state.
  6. O

    State diagram for reversible mod-4-counter

    1. Draw a state diagram for a reversible mod‐4‐counter with the following in signals. 00=stand still in the current statement 10=count up. 01=count down. : 2. The attempt at a solution My first problem is that I'm a bit confused about what "reversible mod-4-counter" means. Do they mean...
  7. H

    Filling Flat Tire - Adiabatic Reversible Process

    Homework Statement A nearly flat bicycle tire becomes noticeably warmer after it has been pumped up. Approximate this process as a reversible adiabatic compression. Take the initial P and T of the air (before it is put into the tire) to be 1.00 bar and 298.0K. The final volume of air (after it...
  8. L

    Reversible vs. Irreversible change (gases)

    Homework Statement I know how to do the problem so I don't need help actually solving it, I just don't understand the concepts. A sample of 4.5g of methane occupies 12.7L at 310k. a) Calculate the work done when the gas expands isothermally against a constant external pressure of 7.7 kPa...
  9. M

    Ideal Gas Under A (Complex) Reversible Process

    Homework Statement An ideal gas undergoes a reversible process 1-2-3-4-5. The stage from 1-2 as well as isobaric 2-3 and isochoric 4-5 stages are represented by linear segments. The Stage 2-3 is isothermal. The following relations are true: V_2=2*V_1 p_2=1.5*p_1 V_3=4*V_1 V_4=6*V_1...
  10. F

    Role of Reversibility in Carnot Cycle Efficiency

    what role dos the reversibility play in making the carnot cycle most efficient?
  11. L

    Thermaldynamics problem, reversible process work done on

    Homework Statement One mole of a monatomic ideal gas is taken through a reversible process from an initial state "a" to a final state "b" during which the pressure of the gas varies with volume V as shown below. Calculate the work Won[/on](a->b) done on the gas during this process...
  12. U

    Entropy change in a reversible isothermal process.

    Homework Statement In a reversible isothermal expansion of an ideal gas, as the gas expands, heat is supplied to it, so that the temperature remains constant. Thus, temperature and hence kinetic energy of the molecules does not change but the 'disorder' of the gas increases as it occupies a...
  13. M

    Finding work done, heat in, and heat out over a reversible thermodynamic cycle

    1. Statement of the Problem One mole of a monatomic ideal gas is taken through the reversible cycle shown. Process bc is an adiabatic expansion, with P_b = 10.0 atm and V_b = 1.00E-3 m^3. Find a) the energy added to the gas as heat, b) the energy leaving the gas as heat, c) the net work done by...
  14. P

    P.Chem1: Internal energy in isothermal, reversible reactions

    I have these two homework problems, as well as solutions. What I do not understand is why the solution for one is not the solution for the other. First problem: A sample consisting of 1.00 mol Ar is expanded isothermally at 0 deg Celc from 22.4 dm3 to 44.8 dm3 reversibly. Calculate q, w, delta...
  15. P

    Reversible and entropy (thermo)

    Homework Statement In my book it says, "only if the transformation is reversible can we use dS=\frac{\delta Q}{T}", but I don't know why? I think even if it's not reversible we also use \delta Q=TdS to solve the thermo problems, don't we? I'm looking forward to your ideas, thanks.
  16. B

    Three species reversible reaction rate

    The problem statement says to derive the concentration as a function of time for the general three species first order reactions. I have attached an image of the problem, so see the image for the reaction. I have written the reaction rates for all the reactions but I am having trouble...
  17. A

    Understanding Carnot's Cycle & Reversible Processes

    Why is it so that along with reversible isothermic processes , reversible adiabatic processes must be taken up to complete carnot's cycle?
  18. U

    Reversible reaction activated only by thermal energy

    Dear all, I am not an expert of Chemistry and I would like to know if there is a reversible reaction that can be activated only by thermal energy. The result of the reaction should be something which can be brough again to the initial state, releasing again the thermal energy stored. I was...
  19. A

    Calculating the Efficiency of a Reversible Refrigerator

    Homework Statement A reversible refrigerator has a coefficient of performance equal to 9.55 What is its efficiency? Homework Equations COP = Qh/W e = W/Qh The Attempt at a Solution I thought e would simply be 1/9.55 = 0.1047 =0.105 (Sig. fig) This answer was incorrect...
  20. W

    Energy Change in Reversible Adiabatic Expansion of a van der Waals gas

    Homework Statement Suppose the equation of state of a gas is Beta p=rho/(1-b rho) - beta a rho^2 where beta=1/kb T, b is a constant and rho is the molecular density, N/V. The internal energy of this gas is given by U=(5/2)N kb T - N a rho Determine the final internal energy of the gas...
  21. C

    Reversible process/entropy thermodynamics

    Homework Statement For a reversible process, while the net entropy change must be zero, does this mean that the entropy of the system and surroundings can change as long as they amount to zero?
  22. S

    Definition of a reversible process

    I have seen a reversible process defined as one in which the system and surroundings are restored to their initial state without change elsewhere. As far as I am aware, the system and the surroundings completely occupy the universe. So, I am failing to understand what elsewhere means in this...
  23. A

    Internally Reversible and Isothermal Processes

    What are Internally reversible processes and why isothermal processes are reversible? Also, Isothermal process are only internally reversible or they can be "externally" reversible?
  24. A

    Reversible Adiabatic Expansion for an Ideal Gas

    Homework Statement 1 mole of a monoatomic gas undergoes reversible expansion from 30 L and 400K to 60 L. The molar heat capacity in this situation is (3/2)R, independent of temperature. Calculate the final pressure and temperature of this process if it is adiabatic. Homework...
  25. J

    Efficiency of a heat engine in a reversible cycle

    Homework Statement A heat engine operates in a reversible cycle with the following steps: (i) An ideal gas characterized by γ = 1.4 expands adiabatically, so that it cools from an initial temperature of 330°C to 30°C. (ii) It is compressed isothermally until it reaches its initial volume...
  26. C

    Isothermal expansion: reversible vs irreversible

    1. A sample of methane of mass 4.5 g occupies 12.7 L at 310 K. Assume that the gas behaves ideally. (a) Calculate the work done when the gas expands isothermally against a constant external pressure of 30.0 kPa until its volume has increased by 3.3 L. (b) Calculate the work that would be done...
  27. B

    Thermal question: Reversible cycle

    Homework Statement Hi all I'm a little confused about work in gases. I thought I knew it now I'm not so sure. Basically I'm answering a question about work done on the gas in a reversible cycle where a change in temperature (T1 -T2)at constant volume (V1) is followed by a change in volume at...
  28. A

    Reversible and irreversible reactions

    I need some clarification on the following points on the reversible and irreversible reactions. In the examples cited in textbooks, for reversible reaction, isothermal expansion and compression are given. But the adiabatic exp and comp are not given. Why is it not included in the list...
  29. S

    Thermodynamics 1st Law: reversible process for batteries?

    How could you ensure that an electric battery produced an electric current reversibly? How could you achieve maximum work from an electric battery? I really have no idea how to solve this. Thanks for your help! (Also sorry I first posted this in advanced physics...i don't know how to...
  30. P

    Reversible vs. pseudostatic processes

    I wonder whether a reversible process has to be quasistatic or at least pseudostatic? (probably there exist some processes involving magnetic field which are reversible but not pseudostatic). Below I define what I mean by a reversible, quasistatic and pseudostatic process. Reversible process...
  31. E

    Reversible adiabatic compression

    Two moles of a diatomic gas occupies a volume of 50 L and is at a pressure 4atm. The gas then undergoes a process: a reversible adiabatic compression, so that is temperature doubles. Find both temperatures, and find the volume and the pressure after the compression process. my thoughts...
  32. A

    Reversible Processes: Isothermal to Adiabatic Transition

    The problem: A red-hot 2.00 kg piece of iron at temperature t1=880k is thrown into a huge lake whose temperature is t2=280K. Assume the lake is so large that its temperature rise is insignificant. The book says that this process is irreversible. Why? I have another question. In a reversible...
  33. K

    No change in entropy of the system+surroundings in reversible process.Really?

    No change in entropy of the system+surroundings in "reversible" process.Really? This is a challenge to the sentense from some basic text. I think reversible is not enough. It has to be ISOTHERMAL, right? Lets me be sure that i am correct!
  34. M

    Quasi equilibrium and non flow reversible in a simpler way?

    Can anyone explain me quasi equilibrium and non flow reversible in a simpler way? It is from thermodynamics and i am getting difficulty to understand it
  35. M

    Thermodynamics: Reversible Compression of Solid Volume V

    Hi, this concerns thermodymanics. A block of volume V is reversibly compressed from pressure P1 to pressure P2 isothermally at temperature T. It goes on to ask about the heat expelled, but that's not my question. It is a solid, obviously not an ideal gas, so I'm sure the internal energy...
  36. K

    Reversible Adiabatic Process Question

    Homework Statement An Ideal Gas at 300K has a volume of 15L and a pressure of 15 atm. Calculate the change when the system goes under a reversible adiabatic expansion to a pressure of 10 atm. Gamma = 5/3. Cv = 1.5R. q = 0(definition of adiabatic processes).Homework Equations dw = P DV...
  37. F

    Is condensation reversible above critical pressure?

    I have a 50% carbon dioxide and 50% nitrogen gas mix at 1800psig, 70*F. Is there a reference source for the dewpoint of the CO2 in that mix? Assuming the temperature falls below that dewpoint and the CO2 condenses, will it return to a mix as the temperature is raised? thanks, kw
  38. E

    Entropy, reversible process

    Homework Statement An ideal gas is taken from an initial temperature Ti to a higher final temperature Tf along two different reversible paths: Path A is at constant pressure; Path B is at constant volume. The relation between the entropy changes of the gas for these paths is a) delta S(A) >...
  39. B

    Reversible & non reversible internal combustion engines

    Please can someone explain clearly in perhaps lay man terms the difference between REVERSIBLE & NON REVERSIBLE INTERNAL COMBUSTION ENGINES. Thanks
  40. K

    Isothermal reversible condensation

    Homework Statement A sample of 1.00 mol H20(g) is condensed isothermally and reversibly to liquid water at 100°C. The standard enthalpy of vaporization of water at 100°C is 40.656 kJ mol-1. Find w, q, change in internal energy, and change in enthalpy for this process. Homework Equations...
  41. T

    Reversible adiabatic expansion

    Homework Statement I'm in a rutt for a tutorial question: The question is basically to show that the work done during a reversible adiabatic expansion of an ideal gas is W = (P1V1 – P2V2)/(1 ‐ γ) ... Y is gamma Homework Equations The Attempt at a Solution I've got so...
  42. N

    Isentropic Process and Reversible Process

    Hi all, Will like to check if my below thoughts are right: 1) For a totally reversible process, it has to be both internally and externally reversible. And the definition of externally reversible means heat transfer between a system and reservoir where the temperature are the same. 2)...
  43. J

    First law of thermodynamics, q=w for a reversible isothermal process

    according to first law of thermodynamics,q=w for a reversible isothermal process.this means all the energy absorbed is being used to to do the work ,but according to second law of thermodynamics,there cannot be 100% effeciency.please tell where i am going wrong
  44. S

    Internal energy of a hydrostatic system in a reversible adiabatic process

    Homework Statement A simple hydrostatic system is such that PV^k is constant in a reversible adiabatic process, where k > 0 is a given constant. Show that its internal energy has the form E=\frac{1}{k-1}PV+NF(\frac{PV^k}{N^k} where f is an arbitrary function. Hint: PV^k must be a function of...
  45. kandelabr

    Reversible exothermic reaction

    hello guys. first, i must say that chemistry never was my beloved subject, that's why I don't know much about it, so please be patient. o.0 well, i need a heat reservoir*. it should have high energy density and should not lose stored energy over time. the heat should be released on demand...
  46. K

    Reversible adiabatic expansion of ideal gas, entropy change?

    Homework Statement One mole of an ideal gas at 0 celcius is subjected to changes below, calculate the change in entropy of the gas: i) Gas is expanded reversibly and isothermally to twice its initial volume. DONE - 5.76 J/K ii)A similar expansion to i. is performed reversibly and...
  47. D

    Why must reversible process proceed slowly?

    Hi. I'm beginning to study thermodynamics. I'm told that an adiabatic process is a process that is thermally insulated and which is reversible. For instance if a piston is thermally insulated and we compress the gas inside, this compression (I'm told) has to be slow. But why must the...
  48. T

    Is change of phase always reversible?

    If not please give me an example. I can't think of any... I also didn't come across any on the Internet...
  49. H

    Is this thermo process reversible?

    Homework Statement If 0.8kg of water at 100 celsius is mixed with 0.8kg of water at 0 celsius, is this process reversible? Homework Equations Entropy: S = mcln(T_2/T_1) The Attempt at a Solution I've already calculated the entropy of the process, which is 81.1 J/K. But how do I...
  50. D

    Why is ATP synthesis reversible on the F1 subunit? What is the point of this?

    Why is ATP synthesis reversible on the F1 subunit? What is the point of this? Why is ATP synthesis reversible on the F1 subunit? What is the point of this? They did some experiment a long time ago where they took F1 subunit and mixed it with ATP and water, with the Oxygen radioisotope...
Back
Top