Temperature
A macroscopic scalar measure of the average translational kinetic energy of constituent particles in a physical system.
Governing formula
1 / T = (∂S / ∂U)_V, E_avg = (3/2) kB T
SI unit
K (°C, °F)
In depth
Thermodynamically, temperature determines the direction of spontaneous heat flow—heat naturally flows from higher temperature to lower temperature systems until thermal equilibrium is established.
Examples in the real world
A glowing stove burner at 800 K having much higher average atomic kinetic energy than an ice cube at 273 K.