Pascal ( unit ) - wikipedia Pascal ( unit ) Pascal A pressure gauge reading in psi ( red scale ) and kPa ( black scale ) Unit information Unit system SI derived unit Unit of Pressure or stress Symbol Pa Named after Blaise Pascal Unit conversions 1 Pa in...... is equal to... SI base units : kg ⋅ m ⋅ s US customary units : 1.450 × 10 psi atmosphere : 9.869 × 10 atm bar : 10 bar The pascal ( symbol : Pa ) is the SI derived unit of pressure used to quantify internal pressure, stress, Young 's modulus and ultimate tensile strength. It is defined as one newton per square metre. It is named after the French polymath Blaise Pascal. 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 one centibar. The unit of measurement called standard atmosphere ( atm ) is defined as 101 325 Pa. Meteorological reports typically state atmospheric pressure in millibars. Contents 1 Etymology 2 Definition 3 Standard units 4 Uses 4.1 Hectopascal and millibar units 5 See also 6 References 7 External links Etymology The unit is named after Blaise Pascal, noted for his contributions to hydrodynamics and hydrostatics, and experiments with a barometer. The name pascal was adopted for the SI unit newton per square metre ( N / m ) by the 14th General Conference on Weights and Measures in 1971. Definition The pascal can be expressed using SI derived units, or alternatively solely SI base units, as : 1 P a = 1 N m 2 = 1 k g m ⋅ s 2 = J m 3 ( displaystyle ( \rm ( 1 ~ Pa = 1 ~ ( \frac ( N ) ( m ^ ( 2 ) ) ) = 1 ~ ( \frac ( kg ) ( m cdot s ^ ( 2 ) ) ) = ( \frac ( J ) ( m ^ ( 3 ) ) ) ) ) ) where N is the newton, m is the metre, kg is the kilogram, s is the second, and J is the joule. One pascal is the pressure exerted by a force of magnitude one newton perpendicularly upon an area of one square metre. Standard units The unit of measurement called an atmosphere or a standard atmosphere ( atm ) is 101 325 Pa ( 101.325 kPa ). This value is often used as a reference pressure and specified as such in some national and international standards, such as the International Organization for Standardization 's ISO 2787 ( pneumatic tools and compressors ), ISO 2533 ( aerospace ) and ISO 5024 ( petroleum ). In contrast, International Union of Pure and Applied Chemistry ( IUPAC ) recommends the use of 100 kPa as a standard pressure when reporting the properties of substances. Unicode has dedicated code - points U + 33A9 Pa Square Pa and U + 33AA kPa Square kPa in the CJK Compatibility block, but these exist only for backward - compatibility with some older ideographic character - sets and are therefore deprecated. Uses This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( January 2016 ) The pascal ( Pa ) or kilopascal ( kPa ) as a unit of pressure measurement is widely used throughout the world and has largely replaced the pounds per square inch ( psi ) unit, except in some countries that still use the imperial measurement system or the US customary system, including the United States. Geophysicists use the gigapascal ( GPa ) in measuring or calculating tectonic stresses and pressures within the Earth. Medical elastography measures tissue stiffness non-invasively with ultrasound or magnetic resonance imaging, and often displays the Young 's modulus or shear modulus of tissue in kilopascals. In materials science and engineering, the pascal measures the stiffness, tensile strength and compressive strength of materials. In engineering use, because the pascal represents a very small quantity, the megapascal ( MPa ) is the preferred unit for these uses. Approximate Young 's modulus for common substances Material Young 's modulus nylon 6 2 -- 4 GPa hemp fibre 35 GPa aluminium 69 GPa tooth enamel 83 GPa copper 117 GPa structural steel 200 GPa diamond 1220 GPa The pascal is also equivalent to the SI unit of energy density, J / m. This applies not only to the thermodynamics of pressurised gases, but also to the energy density of electric, magnetic, and gravitational fields. In measurements of sound pressure or loudness of sound, one pascal is equal to 94 decibels SPL. The quietest sound a human can hear, known as the threshold of hearing, is 0 dB SPL, or 20 μPa. The airtightness of buildings is measured at 50 Pa. Hectopascal and millibar units Main article : Bar ( unit ) The units of atmospheric pressure commonly used in meteorology were formerly the bar, which was close to the average air pressure on Earth, and the millibar. Since the introduction of SI units, meteorologists generally measure pressures in hectopascals ( hPa ) unit, equal to 100 pascals or 1 millibar. Exceptions include Canada, which use kilopascals ( kPa ). In many other fields of science, the SI is preferred, which means Pa with a prefix ( in multiples of 1000 ) is preferred. Many countries also use the millibars. In practically all other fields, the kilopascal ( 1000 pascals ) is used instead. See also Centimetre of water Metric prefix Orders of magnitude ( pressure ) Pascal 's law References Jump up ^ International Bureau of Weights and Measures ( 2006 ), The International System of Units ( SI ) ( PDF ) ( 8th ed. ), p. 118, ISBN 92 - 822 - 2213 - 6, archived ( PDF ) from the original on 2017 - 08 - 14 Jump up ^ `` Definition of the standard atmosphere ''. BIPM. Retrieved 2015 - 02 - 16. Jump up ^ bipm.fr Archived 30 June 2007 at the Wayback Machine. Jump up ^ Table 3 ( Section 2.2. 2 ) Archived 18 June 2007 at the Wayback Machine., SI Brochure, International Bureau of Weights and Measures Jump up ^ `` Resolution 4 of the 10th meeting of the CGPM ''. Conférence Générale des Poids et Mesures ( CGPM ). 1954. Retrieved 2010 - 04 - 05. Jump up ^ IUPAC.org, Gold Book, Standard Pressure Jump up ^ `` CJK Compatibility '' ( PDF ). 2015. Retrieved 2016 - 02 - 21. Jump up ^ `` The Unicode Standard, Version 8.0. 0 ''. Mountain View, CA : The Unicode Consortium. 2015. ISBN 978 - 1 - 936213 - 10 - 8. Retrieved 2016 - 02 - 21. Jump up ^ `` Tensile Modulus - Modulus of Elasticity or Young 's Modulus - for some common Materials ''. Retrieved 2015 - 02 - 16. Jump up ^ `` Chapter 7 ResNet Standards : ResNet National Standard for Home Energy Audits '' ( PDF ). ResNet. 2010. Archived from the original ( PDF ) on 26 July 2011. Retrieved 3 March 2011. Jump up ^ `` KNMI - Weer - Waarnemingen ''. Retrieved 4 December 2016. Jump up ^ `` Comment convertir la pression ? - IRM ''. Retrieved 4 December 2016. Jump up ^ DWD Jump up ^ `` Japan Meteorological Agency - Weather Maps ''. Retrieved 4 December 2016. Jump up ^ MDD Archived 6 May 2006 at the Wayback Machine. Jump up ^ NOAA Jump up ^ Kingdom, Met Office, FitzRoy Road, Exeter, Devon, EX1 3PB, United. `` Key to symbols and terms ''. Retrieved 4 December 2016. Jump up ^ CTV News, weather ; current conditions in Montreal Archived 4 June 2011 at the Wayback Machine. Jump up ^ Canada, Environment. `` Montréal, QC - 7 Day Forecast - Environment Canada ''. Retrieved 4 December 2016. External links hide SI units Authority : International System of Units ( BIPM ) Base units ampere candela kelvin kilogram metre mole second Derived units with special names becquerel coulomb degree Celsius farad gray henry hertz joule katal lumen lux newton ohm pascal radian siemens sievert steradian tesla volt watt weber Other accepted units astronomical unit bar dalton day decibel degree of arc electronvolt hectare hour litre minute minute of arc neper second of arc tonne atomic units natural units See also Conversion of units Metric prefixes Proposed redefinitions Systems of measurement Book Retrieved from `` https://en.wikipedia.org/w/index.php?title=Pascal_(unit)&oldid=834415059 '' Categories : SI derived units Units of pressure Blaise Pascal Hidden categories : Webarchive template wayback links All articles with dead external links Articles with dead external links from December 2017 Articles with permanently dead external links Use dmy dates from October 2011 Pages using deprecated image syntax Articles needing additional references from January 2016 All articles needing additional references All articles with unsourced statements Articles with unsourced statements from January 2016 Talk Contents About Wikipedia Afrikaans Alemannisch Asturianu Azərbaycanca বাংলা Bân - lâm - gú Беларуская Беларуская ( тарашкевіца ) ‎ Български བོད ་ ཡིག Bosanski Brezhoneg Català Čeština Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Հայերեն हिन्दी Hrvatski Bahasa Indonesia Íslenska Italiano עברית ქართული Қазақша Kiswahili Kreyòl ayisyen Latviešu Lietuvių Limburgs Magyar Македонски മലയാളം Bahasa Melayu Монгол Nederlands 日本 語 Nordfriisk Norsk Norsk nynorsk Occitan Oʻzbekcha / ўзбекча ភាសា ខ្មែរ Piemontèis Plattdüütsch Polski Português Română Русский Scots Sicilianu සිංහල Simple English Slovenčina Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska தமிழ் ไทย Türkçe Українська Tiếng Việt 粵語 中文 69 more Edit links This page was last edited on 5 April 2018, at 16 : 24. 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Question: si unit of pressure is pascal which is equal to
Answer: one newton per square metre