Newton (unit)

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Kilonewton
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newton
Sir Isaac Newton
Conversions
1 N in ...... is equal to ...
   SI base units   1 kg⋅m⋅s−2
   CGS units   105 dyn
   Imperial units   0.224809 lbf

The newton (symbol: N) is the unit of force in the International System of Units (SI). It is defined as , the force which gives a mass of 1 kilogram an acceleration of 1 metre per second squared.

It is named after Isaac Newton in recognition of his work on classical mechanics, specifically his second law of motion.

Definition

A newton is defined as (it is a named derived unit defined in terms of the SI base units).[1]: 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.[2]

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 1 metre per second every second.[2]

In 1946, the

MKS system of units to be the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared. In 1948, the 9th CGPM Resolution 7 adopted the name newton 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 the Système international d'unités (SI), or International System of Units.[3]

The newton is named after

common 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 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:[5]

where represents the mass of the object undergoing an acceleration . When using the SI unit of mass, the kilogram (), and SI units for distance metre (), and time, second () we arrive at the SI definition of the newton:

Examples

At average gravity on Earth (conventionally, ), a kilogram mass exerts a force of about 9.8 newtons.

  • An average-sized apple at 200 g exerts about two newtons of force at Earth's surface, which we measure as the apple's weight on Earth.
(where 62 kg is the world average adult mass).[6]

Kilonewtons

A carabiner 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 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]

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 

Conversion factors

Units of force
newton dyne kilogram-force,
kilopond 		pound-force poundal
1 N ≡ 1 kg⋅m/s2 = 105 dyn ≈ 0.10197 kp ≈ 0.22481 lbf ≈ 7.2330 pdl
1 dyn = 10–5 N ≡ 1 g⋅cm/s2 ≈ 1.0197×10−6 kp ≈ 2.2481×10−6 lbf ≈ 7.2330×10−5 pdl
1 kp = 9.80665 N = 980665 dyn ≡ gn × 1 kg ≈ 2.2046 lbf ≈ 70.932 pdl
1 lbf ≈ 4.448222 N ≈ 444822 dyn ≈ 0.45359 kp ≡ gn × 1 lb ≈ 32.174 pdl 
1 pdl ≈ 0.138255 N ≈ 13825 dyn ≈ 0.014098 kp ≈ 0.031081 lbf ≡ 1 lb⋅ft/s2
The value of gn as used in the official definition of the kilogram-force (9.80665 m/s2) is used here for all gravitational units.
Three approaches to units of mass and force or weight[8][9]
Base 		Force Weight Mass
2nd law of motion m = F/a F = W ⋅ a/g F = m ⋅ a
System
BG
 GM EE M
AE
 CGS MTS SI
Acceleration (a) ft/s2 m/s2 ft/s2 m/s2 ft/s2 Gal m/s2 m/s2
Mass (m) slug
hyl
 pound-mass kilogram pound gram tonne kilogram
Force (F),
weight (W) 		pound
kilopond
 pound-force kilopond poundal dyne sthène newton
Pressure (p) pound per square inch
technical atmosphere
 pound-force per square inch standard atmosphere poundal per square foot barye
pieze
 pascal
Standard prefixes for the metric units of measure (multiples)
Prefix name N/A deca hecto kilo mega giga
tera
peta
exa
zetta
yotta
ronna
quetta
Prefix symbol da h k M G T P E Z Y R Q
Factor 100 101 102 103 106 109 1012 1015 1018 1021 1024 1027 1030
Standard prefixes for the metric units of measure (submultiples)
Prefix name N/A deci centi milli micro nano
pico
femto
atto
zepto
yocto
ronto
quecto
Prefix symbol d c m μ n p f a z y r q
Factor 100 10−1 10−2 10−3 10−6 10−9 10−12 10−15 10−18 10−21 10−24 10−27 10−30

See also

References

  1. Bureau International des Poids et Mesures (BIPM). p. 137. Archived
    from the original on 30 September 2021. Retrieved 22 September 2021.
  2. ^ a b "Newton | unit of measurement". Encyclopædia Britannica. 17 December 2020. Archived from the original on 27 September 2019. Retrieved 27 September 2019.
  3. ^
    ISBN 9282220451. Archived from the original
    on 11 May 2016. Retrieved 15 November 2015.
  4. ^ David B. Newell; Eite Tiesinga, eds. (2019). The International System of Units (SI) (PDF) (NIST Special publication 330, 2019 ed.). Gaithersburg, MD: NIST. Retrieved 30 November 2019.
  5. ^ "Table 3. Coherent derived units in the SI with special names and symbols". The International System of Units (SI). International Bureau of Weights and Measures. 2006. Archived from the original on 18 June 2007.
  6. PMID 22709383
    .
  7. ^ Bright, Casandra Marie. "A History of Rock Climbing Gear Technology and Standards." (2014).
  8. doi:10.1021/ie50367a028
    .
  9. doi:10.1021/ie50712a010
    .
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