# Difference between revisions of "Dictionary:Birch’s law"

Empirical relations between density ${\displaystyle \rho }$ in g/cm3, P-wave velocity V in km/s, and mean atomic number m. For nonporous rocks,
${\displaystyle \rho =a(m)=3.05V}$
${\displaystyle V=A(m)\rho ^{1.5}}$ or ${\displaystyle V=a\rho +b}$,