There are only several situations in which the bulk modulus is important. These situations include hydraulic systems, deep ocean (on several occasions), geology system like the Earth, Cosmology. The Pushka equation normally can address the situations in deep ocean and geological system. This author is not aware of any special issues that involve in Cosmology as opposed to geological system. The only issue that was not addressed is the effect on hydraulic systems. The hydraulic system normally refers to systems in which a liquid is used to transmit forces (pressure) for surface of moving object (normally piston) to another object. In theoretical or hypothetical liquids the moving one object (surface) results in movement of the other object under the condition that liquid volume is fix. The movement of the responsive object is unpredictable when the liquid volume or density is a function of the pressure (and temperature due to the friction). In very rapid systems the temperature and pressure varies during the operation significantly. In practical situations, the commercial hydraulic fluid can change due to friction by $$50°C$$. The bulk modulus or the volume for the hydraulic oil changes by more 60%. The change of the bulk modulus by this amount can change the response time significantly. Hence the analysis has to take into account the above effects.