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The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m 2). [1]
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m 2, or kg·m −1 ·s −2). This name for the unit was added in 1971; [7] before that, pressure in SI was expressed in newtons per square metre. Other units of pressure, such as pounds per square inch (lbf/in 2) and bar, are also in common use.
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m −2 or kg·m −1 ·s −2). This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N·m −2. When indicated, the zero reference is stated in parentheses following the unit, for example 101 kPa (abs).
When these fluctuations were explained as a manifestation of changes in atmospheric pressure, the science of meteorology was born. Over time, 760 millimeters of mercury at 0 °C came to be regarded as the standard atmospheric pressure. In honour of Torricelli, the torr was defined as a unit of pressure equal to one millimeter of mercury at 0 °C.
±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 Atmospheric pressure on Mars, < 1% of atmospheric sea-level pressure on Earth [37] 610 Pa 0.089 psi Partial vapor pressure at the triple point of water (611.657 Pa) [38] [39 ...
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).
Force per unit oriented surface area Pa L −1 M T −2: order 2 tensor Surface tension: γ: Energy change per unit change in surface area N/m or J/m 2: M T −2: Thermal conductance κ (or) λ: Measure for the ease with which an object conducts heat W/K L 2 M T −3 Θ −1: extensive Thermal conductivity: λ: Measure for the ease with which a ...
Pressure in water and air. Pascal's law applies for fluids. Pascal's principle is defined as: A change in pressure at any point in an enclosed incompressible fluid at rest is transmitted equally and undiminished to all points in all directions throughout the fluid, and the force due to the pressure acts at right angles to the enclosing walls.