Temperature

Temperature is a physical property of a system that underlies the common notions of hot and cold; something that is hotter has the greater temperature. Temperature is one of the principal parameters of thermodynamics. The temperature of a system is defined as simply the average energy of microscopic motions of a single particle in the system. For a solid, these microscopic motions are principally the vibrations of the constituent atoms about their sites in the solid. For an ideal monatomic gas, the microscopic motions are the translational motions of the constituent gas particles. For multiatomic gas vibrational and rotational motion should be included too.