Thenewton (symbol:N) is the unit offorce in theInternational System of Units (SI). Expressed in terms ofSI base units, it is 1 kg⋅m/s2, the force that accelerates a mass of one kilogram at one metre per second squared.
A newton is defined as 1 kg⋅m/s2 (it is a named derived unit defined in terms of theSI base units).[1]: 137 One newton is, therefore, the force needed toaccelerate onekilogram of mass at the rate of onemetre per second squared in the direction of the applied force.[2]
The units "metre per second squared" can be understood as measuring a rate of change invelocity per unit of time, i.e. an increase in velocity by one metre per second every second.[2]
In 1946, theGeneral Conference on Weights and Measures (CGPM) Resolution 2 standardized the unit of force in theMKS 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 namenewton for this force.[3] The MKS system then became the blueprint for today's SI system of units.[4] The newton thus became the standard unit of force in theSystème international d'unités (SI), orInternational System of Units.[3]
The newton is named afterIsaac Newton. As with everySI unit named after a person, its symbol starts with anupper case letter (N), but when written in full, it follows the rules for capitalisation of acommon noun; i.e.,newton becomes capitalised at the beginning of a sentence and in titles but is otherwise in lower case.
The connection to Newton comes fromNewton'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:[5]where represents themass of the object undergoing an acceleration. When using the SI unit of mass, the kilogram (kg), and SI units for distancemetre (m), and time,second (s) we arrive at the SI definition of the newton: 1 kg⋅m/s2.
Acarabiner used inrock 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.
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.[7]: 11
^David B. Newell; Eite Tiesinga, eds. (2019).The International System of Units (SI)(PDF) (NIST Special publication 330, 2019 ed.). Gaithersburg, MD:NIST. Retrieved30 November 2019.
^Bright, Casandra Marie. "A History of Rock Climbing Gear Technology and Standards." (2014).
^Comings, E. W. (1940). "English Engineering Units and Their Dimensions".Industrial & Engineering Chemistry.32 (7):984–987.doi:10.1021/ie50367a028.
^Klinkenberg, Adrian (1969). "The American Engineering System of Units and Its Dimensional Constant gc".Industrial & Engineering Chemistry.61 (4):53–59.doi:10.1021/ie50712a010.
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