Self-contained breathing apparatus pressure changes with ambient temperature. As temperature decreases, the pressure inside the cylinder decreases. The relationship between the temperature and the pressure of a gas is defined by the formula "PV" = "nRT". (See Universal gas constant.) What is particularly important to understand from the formula is that the temperature is in kelvins, not degrees Fahrenheit. Consider the freezing point of water at 32 °F (0 °C, 273.15 K) and compare it to 96 °F (35.6 °C or 308.71 K; normal human body temperature is 37 °C). While 96 is arithmetically three times 32, the difference in temperature from a
Normal shock tables the tables. Next, the equation below shows the relationship between the post normal shock temperature, formula_14, and the upstream ambient temperature, formula_15. Finally, the ratio of stagnation pressures is shown below where formula_17 is the upstream stagnation pressure and formula_18 occurs after the normal shock. The ratio of stagnation temperatures remains constant across a normal shock since the process is adiabatic. Normal shock tables In aerodynamics, the normal shock tables are a series of tabulated data listing the various properties before and after the occurrence of a normal shock wave. With a given upstream Mach number, the post-shock Mach number