The root mean square speed, c_{rms}, can be related to macroscopic properties;

By considering the rate of change of the momentum of particles colliding elastically with a wall, we can find the equation: **pV = nM(c**_{rms}**)**^{2}**/3** where

n = moles of gas

M = molecular mass in Kgmol^{-1 }p = pressure

V = volume of the container

And since we know for a perfect gas **pV = nRT**, we have **RT = M(c**_{rms}**)**^{2}**/3**, where

R = universal gas constant

T = temperature in K