ratio of the relative variation in pressure to the corresponding relative variation in density under elementary reversible adiabatic (isentropic) transformation conditions, rõhu suhtelise muutuse ja vastava suhtelise tiheduse muutuse suhe pöörduva adiabaatilise (isentroopse) elementaarmuundamise tingimustes, ratio of the relative variation in pressure to the corresponding relative variation in density under isentropic process