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Fluids

Kinetic energy and temperature

Although the formula

E_kin(1 molecule) = 3kT/2

has been derived under some simplifying assumptions, it is generally valid for an ideal gas of molecules which do not have further degrees of freedom than their velocity.
Hence, the total kinetic energy of a quantity of N molecules is given by

E_kin(N molecules) = 3NkT/2

By using the ideal-gas law, we can also write

E_kin(N molecules) = 3PV/2

The latter formula will be useful in practical calculus.

isobaric process