Newton (unit)

A newton is defined as 1 kg⋅m/s² (it is a named derived unit defined in terms of the SI base units).{{cite book |last=Bureau International des Poids et Mesures |url=https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf/2d2b50bf-f2b4-9661-f402-5f9d66e4b507?version=1.10&download=true |title=The International System of Units (SI) |publisher=Bureau International des Poids et Mesures (BIPM) |year=2019 |edition=9 |page=137 |format=PDF |access-date=22 September 2021 |archive-date=30 September 2021 |archive-url=https://web.archive.org/web/20210930221014/https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf/2d2b50bf-f2b4-9661-f402-5f9d66e4b507?version=1.10&download=true |url-status=live }}{{rp|137}} One newton is, therefore, the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force.{{Cite web |date=17 December 2020 |title=Newton {{!}} unit of measurement |url=https://www.britannica.com/science/newton-unit-of-measurement |url-status=live |archive-url=https://web.archive.org/web/20190927032140/https://www.britannica.com/science/newton-unit-of-measurement |archive-date=27 September 2019 |access-date=27 September 2019 |work=Encyclopædia Britannica}}

The units "metre per second squared" can be understood as measuring a rate of change in velocity per unit of time, i.e. an increase in velocity by one metre per second every second.

In 1946, the General Conference on Weights and Measures (CGPM) Resolution 2 standardized the unit of force in the MKS system of units to be the amount needed to accelerate one kilogram of mass at the rate of one metre per second squared. In 1948, the 9th CGPM Resolution 7 adopted the name newton for this force.{{Cite book |last= |first= |url=https://books.google.com/books?id=YvZNdSdeCnEC&pg=PA17 |title=The International System of Units (SI) |publisher=U.S. Department of Commerce, National Bureau of Standards |year=1977 |isbn= 9282220451 |edition=1977 |pages=17| access-date = 15 November 2015 | archive-date = 11 May 2016 | archive-url=https://web.archive.org/web/20160511160701/https://books.google.com/books?id=YvZNdSdeCnEC&pg=PA17}} The MKS system then became the blueprint for today's SI system of units.{{cite book |editor1=David B. Newell |editor2=Eite Tiesinga |title=The International System of Units (SI) |url=https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.330-2019.pdf |access-date=30 November 2019 |publisher=NIST |location=Gaithersburg, MD |date=2019|edition=NIST Special publication 330, 2019}} The newton thus became the standard unit of force in the {{lang|fr|Système international d'unités}} (SI), or International System of Units.

{{SI unit lowercase|Isaac Newton|newton|N}}

The connection to Newton comes from Newton's second law of motion, which states that the force exerted on an object is directly proportional to the acceleration hence acquired by that object, thus:{{cite web | title = Table 3. Coherent derived units in the SI with special names and symbols | work = The International System of Units (SI) | publisher = International Bureau of Weights and Measures | year = 2006 |url=http://www.bipm.org/en/si/si_brochure/chapter2/2-2/table3.html | url-status = dead | archive-url=https://web.archive.org/web/20070618123613/http://www.bipm.org/en/si/si_brochure/chapter2/2-2/table3.html | archive-date = 18 June 2007 }}

$$F\; =\; ma,$$

where $m$ represents the mass of the object undergoing an acceleration $a$. When using the SI unit of mass, the kilogram (kg), and SI units for distance metre (m), and time, second (s) we arrive at the SI definition of the newton: 1 kg⋅m/s².

At average gravity on Earth (conventionally, $g\_\backslash text\{n\}$ = {{val|9.80665|u=m/s2}}), a kilogram mass exerts a force of about 9.81 N.

• An average-sized apple with mass 200 g exerts about two newtons of force at Earth's surface, which we measure as the apple's weight on Earth.

: $0.200\; \backslash text\{\; kg\}\; \backslash times\; 9.80665\; \backslash text\{\; m/s\}^2\; =\; 1.961\backslash text\; \{\; N\}.$

• An average adult exerts a force of about 608 N on Earth.

: $62\backslash text\; \{\; kg\}\; \backslash times\; 9.80665\; \backslash text\{\; m/s\}^2=608\backslash text\{\; N\}$ (where 62 kg is the world average adult mass).{{cite journal |last1=Walpole |first1=Sarah Catherine |last2=Prieto-Merino |first2=David |last3=Edwards |first3=Phillip |last4=Cleland |first4=John |last5=Stevens |first5=Gretchen |last6=Roberts |first6=Ian |display-authors=2 |date=18 June 2012 |title=The weight of nations: an estimation of adult human biomass |journal=BMC Public Health |volume=12 |issue=12 |page=439 |doi=10.1186/1471-2458-12-439 |pmc=3408371 |pmid=22709383 |doi-access=free }}

File:Dwire carabiner.jpg used in rock climbing, with a safety rating of 26 kN when loaded along the spine with the gate closed, 8 kN when loaded perpendicular to the spine, and 10 kN when loaded along the spine with the gate open.]]

Large forces may be expressed in kilonewtons (kN), where {{nowrap|1 kN {{=}} 1000 N}}. For example, the tractive effort of a Class Y steam train locomotive and the thrust of an F100 jet engine are both around 130 kN.{{Citation needed|date=January 2024}}

Climbing ropes are tested by assuming a human can withstand a fall that creates 12 kN of force. The ropes must not break when tested against 5 such falls.Bright, Casandra Marie. "A History of Rock Climbing Gear Technology and Standards." (2014).{{rp|11}}

{{Units of force}}

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• Force gauge
• International System of Units (SI)
• Joule, SI unit of energy, 1 newton exerted over a displacement of 1 metre
• Kilogram-force, force exerted by Earth's gravity at sea level on one kilogram of mass
• Kip (unit)
• Pascal, SI unit of pressure, 1 newton acting on an area of 1 square metre
• Orders of magnitude (force)
• Pound (force)
• Sthène
• Newton metre, SI unit of torque

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{{SI units}}

{{Isaac Newton}}

Category:Units of force

Category:SI derived units

Category:Isaac Newton