Kinetic theory
The molecular theory explaining gas behaviour as arising from random particle motion. Kinetic theory predicts that pressure p = (1/3)ρc² (where ρ is gas density and c is root-mean-square speed) and relates internal energy to particle kinetic energy: U = (3/2)NkT (for a monatomic ideal gas). Kinetic theory bridges microscopic particle motion and macroscopic observable properties.
Formula
p = ⅓ρ⟨c²⟩
Real World
The tyres on a Formula 1 car warm up during a race, increasing the average kinetic energy of nitrogen molecules inside and raising tyre pressure — teams monitor this to maintain optimal grip.
Exam Focus
When deriving pressure from kinetic theory, clearly state each assumption (elastic collisions, random motion, negligible volume) — derivation marks depend on these.
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