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For gases, pressure is sometimes measured not as an absolute pressure, but relative to atmospheric pressure; such measurements are called gauge pressure. An example of this is the air pressure in an automobile tire, which might be said to be "220 kPa (32 psi)", but is actually 220 kPa (32 psi) above atmospheric pressure. Since atmospheric ...
Pressure gradient: Pressure per unit distance pascal/m L −2 M 1 T −2: vector Temperature gradient: steepest rate of temperature change at a particular location K/m L −1 Θ: vector Torque: τ: Product of a force and the perpendicular distance of the force from the point about which it is exerted
The units of atmospheric pressure commonly used in meteorology were formerly the bar (100,000 Pa), which is close to the average air pressure on Earth, and the millibar. Since the introduction of SI units , meteorologists generally measure atmospheric pressure in hectopascals (hPa), equal to 100 pascals or 1 millibar.
The dimension of the physical quantity pressure P is ... Following are tables of commonly occurring expressions in physics, related to the dimensions of energy ...
Pressure due to direct impact of a strong breeze (~28 mph or 45 km/h) [27] [28] [31] 120 Pa Pressure from the weight of a U.S. quarter lying flat [32] [33] 133 Pa 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
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).
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.
Other units of pressure include: The bar (symbol: bar), defined as 100 kPa exactly. The atmosphere (symbol: atm), defined as 101.325 kPa exactly. These four pressure units are used in different settings. For example, the bar is used in meteorology to report atmospheric pressures. [7] The torr is used in high-vacuum physics and engineering. [8] [9]