The pressure and density of a diatomic gas γ=75 change adiabatically from (P,d) to P′,d′. If d′d=32, then the value of P′/P is ________________.
PVγ=P′V′γ
Pmγdγ=P′m′γd′γ⇒P′P=d′dγ=(32)7/5=128