Thermodynamics

Pressure (Kinetic Theory)

Pressure from molecular collisions. Connects microscopic motion to macroscopic pressure.

Variables

P
Pressure
Gas pressure
Pa
ρ
Density
Mass density
kg/m³
⟨v²⟩
Mean square speed
Average of v²
m²/s²
N
Number of molecules
Total molecules
unitless
V
Volume
Container volume
KE_avg
Average KE
Average kinetic energy per molecule
J

Derivation

From momentum transfer of molecules hitting walls: P = (1/3)ρ⟨v²⟩ = (1/3)(Nm/V)⟨v²⟩ = (2/3)(N/V)KE_avg.

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