Mumbai university > Mechanical Engineering > Sem 3 > Thermodynamics

Marks: 4M

Year: Dec 2015

The Zeroth law deals with thermal equilibrium and establishes a concept of temperature. Zeroth law of thermodynamics states that if two systems are each equal in temperature to a third, they are equal in temperature to each other.

For eg: System ‘1’ may consist of a mass of gas enclosed in a rigid vessel fitted with a pressure gauge. If there is no change of pressure when this system is brought into contact with system ‘2’ a block of iron, then the two systems are equal in temperature (assuming that the systems 1 and 2 do not react each other chemically or electrically). Experiment reveals that if system ‘1’ is brought into contact with a third system ‘3’ again with no change of properties then systems ‘2’ and ‘3’ will show no change in their properties when brought into contact provided they do not react with each other chemically or electrically. Therefore, ‘2’ and ‘3’ must be in equilibrium.