Mean Free Path Calculator
Compute average distance traveled between collisions for gas molecules.
How to Use This Calculator
Enter the gas temperature, an estimate of molecular diameter, and the pressure. The result is the mean free path in meters.
Formula
λ = kB T / (√2 · π · d² · p)
Example: T=300 K, d=3.7e−10 m, p=101325 Pa → λ ≈ 6.8e−8 m
About Mean Free Path
In kinetic theory, mean free path is the average distance a particle travels between collisions, depending on temperature, pressure, and particle size.
Frequently Asked Questions
Which diameter should I use?
Use an effective molecular diameter from literature (e.g., N₂ ≈ 3.7×10⁻¹⁰ m).
How does altitude affect λ?
Lower pressure at high altitude increases mean free path.