Why do uranium-235 hexafluoride molecules pass through a porous barrier faster than uranium-238 hexafluoride molecules?

Uranium-235 hexafluoride (${}^{235}{\text{UF}}_6$) molecules pass through a porous barrier faster than uranium-238 hexafluoride (${}^{238}{\text{UF}}_6$) molecules due to the principles of the kinetic theory of gases.

According to this theory, at a constant temperature, gas molecules with less mass possess a higher average velocity than heavier molecules. Because the ${}^{235}\text{U}$ isotope is lighter than the ${}^{238}\text{U}$ isotope, the resulting ${}^{235}{\text{UF}}_6$ molecules travel at a greater average speed. This velocity difference allows the ${}^{235}{\text{UF}}_6$ molecules to traverse the porous barrier more rapidly than the heavier ${}^{238}{\text{UF}}_6$ molecules, a phenomenon utilized in the gaseous diffusion method to enrich uranium for use in nuclear reactors and weapons.1