What does temperature measure?

Temperature measures the average kinetic energy of particles in a substance. Kinetic energy refers to the energy that an object possesses due to its motion. In the context of temperature, as the particles within a material move faster, the temperature is higher because the average kinetic energy increases. This relationship is fundamental in thermodynamics, where temperature is used as a measure of thermal energy.

Understanding temperature in this way distinguishes it from other concepts. For example, while total energy of molecular motion might seem related, it encompasses both kinetic and potential energy, rather than exclusively focusing on the average kinetic energy that defines temperature. Similarly, heat content, often represented by the term enthalpy, refers to the total internal energy of the system, factoring in other elements like phase or chemical composition. Volume is a physical property of a substance that denotes how much space it occupies but does not directly relate to the concept of temperature. Thus, recognizing that temperature specifically reflects average kinetic energy is essential for grasping its role in physical science.