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In fluid dynamics, dynamic pressure (denoted by q or Q and sometimes called velocity pressure) is the quantity defined by: [1] = where (in SI units): q is the dynamic pressure in pascals (i.e., N/m 2, ρ (Greek letter rho) is the fluid mass density (e.g. in kg/m 3), and; u is the flow speed in m/s.
The bar is a metric unit of pressure defined as 100,000 Pa (100 kPa), though not part of the International System of Units (SI). A pressure of 1 bar is slightly less than the current average atmospheric pressure on Earth at sea level (approximately 1.013 bar).
Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 1 bar (100 kPa, 10 5 Pa). NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa). [3] This standard is also called normal temperature and pressure (abbreviated as NTP).
The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m 2). [1] It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar , and the kilopascal (1 kPa = 1000 Pa), which is equal to ...
Download as PDF; Printable version; In other projects Wikidata item; Appearance. move to sidebar hide ... 1 bar 10 5 — = 1.0197 = 0.986 92 = 750.06 = 14.503 773 773 ...
1 torr ≈ 1 mmHg [34] ±200 Pa ~140 dB: Threshold of pain pressure level for sound where prolonged exposure may lead to hearing loss [citation needed] ±300 Pa ±0.043 psi Lung air pressure difference moving the normal breaths of a person (only 0.3% of standard atmospheric pressure) [35] [36] 400–900 Pa 0.06–0.13 psi
1 bar = 1 000 000 dynes/square centimetre; But these definitions are equivalent, so it makes no sense to say one is the "old" definition. A change of units in the way the definition is worded is not a change in definition! 1 bar = 10^6 dynes/(cm)^2 = 10^6 (10^(-5)) N/(10^(-2) m)^2 = 10 N/10^(-4) m^2 = 10^5 N/m^2 = 10^5 pascals
The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at 0 °C (32 °F) and standard gravity (g n = 9.806 65 m/s 2). [2] It was used as a reference condition for physical and chemical properties, and the definition of the centigrade temperature scale set 100 °C as the boiling point of water at this pressure.