Name: thermal equilibrium and the zeroth law
Uploaded: 2025-05-22T09:05:48.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Energy

HS-PS3-4

Zeroth Law of Thermodynamics

La legge zero della termodinamica afferma che se due corpi sono in equilibrio termico con un terzo corpo, sono anche in equilibrio termico l'uno con l'altro.
Per capirlo sperimentalmente, considera tre bicchieri riempiti d'acqua a tre diverse temperature.
Dopo aver collegato il bicchiere A con B e il bicchiere B con C, avrà luogo il trasferimento di calore.
Dopo un certo periodo di tempo, l'acqua nel becher A raggiunge l'equilibrio termico con l'acqua nel becher B, e l'acqua nel becher B raggiunge l'equilibrio con l'acqua nel becher C.
Registrando la temperatura dei becher, si osserva una temperatura uniforme in tutti e tre i becher, che corrisponde alla legge zero della termodinamica.
L'applicazione più significativa della legge zero della termodinamica sono i diversi tipi di termometri.
Quando un termometro viene utilizzato per misurare la temperatura di un corpo, raggiunge l'equilibrio termico modificando la propria temperatura.
Pertanto, la temperatura misurata del corpo è in realtà la temperatura del termometro.

<ol>
	<li>OpenStax. (2019). Fisica universitaria Vol. 2. [Versione web]. Estratto da <a href="https://openstax.org/books/university-physics-volume-2/pages/1-1-temperature-and-thermal-equilibrium">https://openstax.org/books/university-physics-volume-2/pages/1-1-temperature-and-thermal-equilibrium</a></li>
</ol>

principio zero della termodinamica

Sperimentalmente, se l'oggetto A è in equilibrio con l'oggetto B, e l'oggetto B è in equilibrio con l'oggetto C, allora l'oggetto A è in equilibrio con l'oggetto C. Questa affermazione di transitività è chiamata il principio zero della termodinamica. Per esempio, un freddo blocco di metallo e un blocco di metallo caldo sono entrambi posizionati su una piastra a temperatura ambiente. Alla fine, il blocco freddo e la piastra saranno in equilibrio termico. Inoltre, il blocco caldo e la piastra saranno in equilibrio termico. Grazie al principio zero della termodinamica, possiamo concludere che anche il blocco caldo e quello freddo sono in equilibrio termico.

Il fisico britannico Ralph Fowler suggerì il numero “zero” nel 1930. A quel tempo, la prima, la seconda, e la terza legge della termodinamica erano già nominate e numerate. Il principio zero era stato raramente dichiarato, ma necessitava di essere trattato prima degli altri, così Fowler gli diede un numero minore.

Ora consideriamo il caso in cui A è un termometro. Il principio zero ci dice che se A legge una certa temperatura quando è in equilibrio con B, ed è posizionato in contatto con C, non scambierà energia con quest'ultimo, di conseguenza la sua lettura della temperatura rimarrà la stessa. In altre parole, se due oggetti sono in equilibrio termico, hanno la stessa temperatura.

Principio zero della termodinamica

Sperimentalmente, se l'oggetto A è in equilibrio con l'oggetto B, e l'oggetto B è in equilibrio con l'oggetto C, allora l'oggetto A è in equilibrio con l'oggetto C.

Education

Didattica

JoVE Core

Physics

Fisica

Unit 1

Unità 1

Temperature and Heat

Temperatura e Calore

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

thermal equilibrium and the zeroth law

The zeroth law of thermodynamics explains thermal equilibrium between objects. If object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is also in equilibrium with object C. This transitive relationship is the key idea behind the law.

A simple example uses metal blocks and a metal plate at room temperature. A cold metal block and a hot metal block are both placed on the plate. Over time, the cold block and the plate reach thermal equilibrium, and the hot block and the plate do too. By the zeroth law, the cold block and the hot block are then also in thermal equilibrium.

The law also helps explain how thermometers work. If a thermometer is in equilibrium with one object and then placed in contact with another object, it will not exchange energy with that object if their temperatures match. Its reading stays the same. In other words, two objects in thermal equilibrium have the same temperature.

The name zeroth law was suggested by British physicist Ralph Fowler in the 1930s. By then, the first, second, and third laws of thermodynamics had already been named. The zeroth law was less often stated, but it had to be discussed before the others, so Fowler gave it the smaller number.

Thermal Equilibrium and the Zeroth Law

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zeroth law of thermodynamics

The zeroth law of thermodynamics explains thermal equilibrium between objects. If object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is also in equilibrium with object C. This transitive relationship is the key idea behind the law. A simple example uses metal blocks and a metal plate at room temperature. A cold metal block and a hot metal block are both placed on the plate. Over time, the cold block and the plate reach thermal equilibrium, and...

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Learn how the zeroth law of thermodynamics shows that objects in thermal equilibrium have the same temperature and why this matters for thermometers.

Thermal Equilibrium and the Zeroth Law | JoVE K12

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HS-PS3-6

Thermal Equilibrium and the Zeroth Law

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