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The amount of mass that can be lifted by hydrogen in air per unit volume at sea level, equal to the density difference between hydrogen and air, is: (1.292 - 0.090) kg/m 3 = 1.202 kg/m 3. and the buoyant force for one m 3 of hydrogen in air at sea level is: 1 m 3 × 1.202 kg/m 3 × 9.8 N/kg= 11.8 N
The density of air at sea level is about 1.2 kg/m 3 (1.2 g/L, 0.0012 g/cm 3). Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the ideal gas law ).
Standard sea-level conditions (SSL), [1] also known as sea-level standard (SLS), defines a set of atmospheric conditions for physical calculations.The term "standard sea level" is used to indicate that values of properties are to be taken to be the same as those standard at sea level, and is done to define values for use in general calculations.
where a 0 is 1,225 km/h (661.45 kn) (the standard speed of sound at 15 °C), M is the Mach number, P is static pressure, and P 0 is standard sea level pressure (1013.25 hPa). Combining the above with the expression for Mach number gives EAS as a function of impact pressure and static pressure (valid for subsonic flow):
For example, while sound travels at 343 m/s in air, it travels at 1481 m/s in water (almost 4.3 times as fast) and at 5120 m/s in iron (almost 15 times as fast). In an exceptionally stiff material such as diamond , sound travels at 12,000 m/s (39,370 ft/s), [ 2 ] – about 35 times its speed in air and about the fastest it can travel under ...
[citation needed] Pure liquid water is 1,000 kg/m 3 (62 lb/cu ft). Air density is a property used in many branches of science, engineering, and industry, including aeronautics; [2] [3] [4] gravimetric analysis; [5] the air-conditioning industry; [6] atmospheric research and meteorology; [7] [8] [9] agricultural engineering (modeling and ...
The speed of sound in a liquid is given by = / where is the bulk modulus of the liquid and the density. As an example, water has a bulk modulus of about 2.2 GPa and a density of 1000 kg/m 3, which gives c = 1.5 km/s. [38]
ρ (Greek letter rho) is the fluid mass density (e.g. in kg/m 3), and; u is the flow speed in m/s. It can be thought of as the fluid's kinetic energy per unit volume. For incompressible flow, the dynamic pressure of a fluid is the difference between its total pressure and static pressure. From Bernoulli's law, dynamic pressure is given by