The Kinetic Theory of Gases in Physics

Pressure and temperature look like properties of a gas, but they are really the summed behaviour of an enormous number of tiny particles bouncing off the walls. Kinetic theory makes that leap, and it is why the gas laws work at all. Every push on the container is a molecule changing direction, so the pressure a gas exerts is just the average kinetic energy of its molecules multiplied out over the volume, and temperature turns out to measure that average energy directly. Two gases at the same temperature therefore hold the same energy per molecule no matter how different they are. The blocks take that molecular picture, the characteristic speeds it predicts, the energy each kind of molecule can store, and the relations that govern a gas expanding without any heat entering it.