Zeroth Law Temperature

Overview

Engineering reference data for Zeroth Law Temperature in thermodynamics.

Key Formulas

First Law

$\Delta U = Q - W$

Energy is conserved — heat added minus work done.

Ideal Gas Law

$PV = nRT$

Relates pressure, volume, and temperature of an ideal gas.

Heat Transfer

$Q = mc\Delta T$

Sensible heat transfer.

Carnot Efficiency

$\eta = 1 - T_C/T_H$

Maximum efficiency between two temperatures.

Variables

Symbol	Description	Unit
$U$	Internal energy	J
$Q$	Heat	J
$W$	Work	J
$P$	Pressure	Pa
$V$	Volume	m³
$T$	Temperature	K

Physical Interpretation

The Zeroth Law establishes temperature as a fundamental and measurable property of a system, distinct from heat itself. It asserts that thermal equilibrium is a transitive relation. If system A is in thermal equilibrium with system C, and system B is in thermal equilibrium with system C, then system A must be in thermal equilibrium with system B. This transitive property allows for the consistent definition and calibration of temperature scales.

Practical Applications

This law is the foundational principle behind all temperature measurement. A thermometer (system C) is brought into thermal contact with a system of interest (system A). When they reach thermal equilibrium, the thermometer's reading indicates the system's temperature. This same thermometer can then be used to compare temperatures of other systems (B, D, etc.), ensuring consistent and comparable measurements across different objects and environments.

References

• Original Source