Pressure (Kinetic Theory)
Pressure from molecular collisions. Connects microscopic motion to macroscopic pressure.
Variables
Derivation
From momentum transfer of molecules hitting walls: P = (1/3)ρ⟨v²⟩ = (1/3)(Nm/V)⟨v²⟩ = (2/3)(N/V)KE_avg.
Your notes
Other thermodynamics formulas with the same quantities
- Ideal Gas Law (Molecular) (Kinetic Theory) shares Pressure, Volume, Number of molecules
- Adiabatic Process (First Law) shares Pressure, Volume
- Enthalpy (First Law) shares Pressure, Volume
- Mean Free Path (Kinetic Theory) shares Pressure
- Work Done by Gas (First Law) shares Pressure
Where this formula is listed
- Thermodynamics formulas, under Kinetic Theory, alongside Most Probable Speed and Mean Speed.
- In the thermodynamics list it comes after Mean Free Path and before Most Probable Speed.
- Thermodynamics formula sheet, one of 34 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Pressure (Kinetic Theory) formula?
Pressure (Kinetic Theory) is written P = (1/3)ρ⟨v²⟩ = (2/3)(N/V)KE_avg. Pressure from molecular collisions. Connects microscopic motion to macroscopic pressure. It belongs to Thermodynamics, under Kinetic Theory.
What are the units in P = (1/3)ρ⟨v²⟩ = (2/3)(N/V)KE_avg?
In SI units, P is pressure, measured in kg/(m·s²); ρ is density, measured in kg/m³; ⟨v²⟩ is mean square speed, measured in m²/s²; N is number of molecules (dimensionless); V is volume, measured in m³; KE_a vg is average ke, measured in kg·m²/s².
How is the Pressure (Kinetic Theory) formula derived?
From momentum transfer of molecules hitting walls: P = (1/3)ρ⟨v²⟩ = (1/3)(Nm/V)⟨v²⟩ = (2/3)(N/V)KE_avg. The result is P = (1/3)ρ⟨v²⟩ = (2/3)(N/V)KE_avg.