What is Zeroth law: Definition and 14 Discussions

The zeroth law of thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. Accordingly, thermal equilibrium between systems is a transitive relation.
Two systems are said to be in thermal equilibrium with respect to each other if they are linked by a wall permeable only to heat and they do not change over time. As a convenience of language, the same is also sometimes said of unlinked systems that would not change if they did have such a wall.
The physical meaning is expressed by Maxwell in the statement: "All heat is of the same kind". Another statement of the law is "All diathermal walls are equivalent".The law is important for the mathematical formulation of thermodynamics, which depends on the assertion that the relation of thermal equilibrium is an equivalence relation, The condition justifies the use of practical thermometers.

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  1. QuasarBoy543298

    Question about the 0th law of thermodynamics

    assume I have 3 systems a,b and c. the equilibrium between a and c can be described by the equality PcVc = f(A1,..., An) and the same for b and c - PcVc = g(B1,...,Bk). why does the equality g(B1,..., Bk) = f(A1,..., An) describes an equilibrium between A and B? the 0th law states that if A and...
  2. 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...
  3. A

    How can the simplification of equation I.4 using equation I.5 be justified?

    I was studying zeroth law from MIT Courseware (http://ocw.mit.edu/courses/physics/8-333-statistical-mechanics-i-statistical-mechanics-of-particles-fall-2013/lecture-notes/MIT8_333F13_Lec1.pdf). On page 2, it is mentioned that equation I.4 can be simplified using equation I.5 by cancelling the...
  4. J

    What is the Zeroth Law of Thermodynamics and why is it causing confusion?

    This is not a homework problem. I want to relay a statement made by my professor. From his online script: "0th law of thermodynamics: If two subsystems I,II are separately in thermal contact with a third system, III, then they are in thermal equilibrium with each other." He stated this in...
  5. Ravyan Asro

    Does temperature in special relativity depend on the frame of observation?

    if two bodies are in thermal equilibrium in one frame, will they be in thermal equilibrium in all frames? also, does the temperature of a body depend on the frame from which it is observed?
  6. T

    Zeroth law of thermodynamics and empirical temperature

    In these lecture notes (http://ocw.mit.edu/courses/physics/8-333-statistical-mechanics-i-statistical-mechanics-of-particles-fall-2007/lecture-notes/lec1.pdf ), they get the equation: F_{AC} (A_1, A_2, \ldots; C_2, C_3, \ldots) = F_{BC} (B_1, B_2, \ldots; C_2, C_3, \ldots) Then they claim...
  7. B

    Zeroth law of thermodynamic and definition of temperature

    Hello everybody, I am a new member and do not know what is the best way to asking question. in "Statical physics of particle , m.kardar" . how he derived eq1.6 ? he said that we can eliminate "C" from eq1.4, but how? http://libgen.org/book/index.php?md5=BC07A3BDB70689E0E612DED12C96CC78 the book...
  8. L

    Question related to Zeroth law of thermodynamics

    I have given enough thought to this but couldn't get anywhere.I would be glad if you express your thoughts on this. Q:Zeroth law of thermodynamics is not valid for which one of the following, (a) 50 ml of water at 25°C is mixed with 150 ml of water at 25°C (b) 500 ml of milk at 15°C...
  9. R

    Is there an equation to prove the Zeroth law of thermodynamics?

    Is there a formula/equation that proves the Zeroth law, that can be confirmed by experiments? And another quick question. If I bunch together three temperatures (all water, of the same volume). Let's say 10 degrees Celsius, 5 degrees Celsius and 15 degrees Celsius. Is there an way of working...
  10. D

    Zeroth law of thermodynamics and thermometers

    the 0th law of thermodynamics states that if 2 systems A and C are in thermodynamic equilibrium with a 3rd system B, then A and C are in thermodynamic equilibrium. in other words, if A has the same temperature as B and B has the same temperature as C, then A has the same temperature as C...
  11. D

    Is Newtons law of cooling related to the zeroth law of thermodynamics?

    Being that both laws explain some kind of heat transfer I was wondering if they are in any way related.
  12. T

    Zeroth law of thermodynamics in terms of heat

    Is there any definition of the zeroth law of termodynamics using the heat concept? And does the zeroth law imply that the only way 2 systems can transfer energy is if they're not in thermal equilibrium? If 1 system is transferring energy to another one, that means they're not in thermal...
  13. L

    Feynman Lectures and the Zeroth Law of Thermodynamics

    In Volume 1 of the Feynman Lectures on Physics, Feynman derives the ideal gas law from Newton's laws of motion. But then on page 41-1, he puts a caveat to the derivation he has just completed: "We have perpetually been making a certain important assumption, which is that if a given system is in...
  14. B

    Zeroth Law of Thermodynamics

    Is there a set average temperature for the universe? And taking into consideration our habitable temperature is x being closer to y than z. If so where does zeroth law of thermodynamics fit? x='s Earth's surface average temperature y='s absolute zero z='s surface of the sun What percentage...