9.4 The First Law of Thermodynamics

A gas’s internal energy can be seen as its total energy. Internal energy is a sum of the potential energy and kinetic energy in the gas. However, potential energy is defined as energy associated with conservative forces, such as gravity or electromagnetic forces. In ideal gases, the particles do not interact with each other with any forces, meaning ideal gasses have no potential energy. Now, we can see that the total internal energy of an ideal gas is just the sum of all of the kinetic energies of the individual particles in the gas.