Thermal Physics & Ideal Gases

Internal energy and temperature

The internal energy of a system is the sum of the random kinetic and potential energies of its molecules. Heating raises internal energy; temperature is a measure of the average kinetic energy of the molecules. The thermodynamic (kelvin) scale: $T(\text{K}) = \theta(^\circ\text{C}) + 273.15$. Absolute zero (0 K) is the temperature at which molecules have minimum internal energy.