The zeroth law of thermodynamics states that if twothermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.
More simply:
if
It is called the zeroth (0th) law of thermodynamics because it was discovered after the others, but people thought it was more important so they wanted to give it a number before the other laws.
The first law of thermodynamics is the application of the conservation of energy principle to heat and thermodynamic processes:
If Q is the energy supplied to the system U the change in internal energy, and W the work done on the environment, First Law of Thermodynamics states that