Newton (unit)
Unit of force in physics
The newton (symbol: N) is the unit of force in the International System of Units (SI). Expressed in terms of SI base units, it is 1 kg⋅m/s2, the force that accelerates a mass of one kilogram at one metre per second squared.
The unit is named after Isaac Newton in recognition of his work on classical mechanics, specifically his second law of motion.
01Definition
A newton is defined as 1 kg⋅m/s2 (it is a named derived unit defined in terms of the SI base units). 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.
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. The MKS system then became the blueprint for today's SI system of units. The newton thus became the standard unit of force in the Système international d'unités (SI), or International System of Units.
The newton is named after Isaac Newton. As with every SI unit named after a person, its symbol starts with an upper case letter (N), but when written in full, it follows the rules for capitalisation of a 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:
02Examples
At average gravity on Earth (conventionally, 
- 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.
- An average adult exerts a force of about 608 N on Earth.
(where 62 kg is the world average adult mass).
03Kilonewtons
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.
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.
04Conversion factors
| Newtons | Dynes | Kilograms-force kiloponds |
Pounds | Poundals | |
|---|---|---|---|---|---|
| 1 N | ≡ 1 kg⋅m⁄s2 | = 100000 dyn | ≈ 0.10197 kgf | ≈ 0.22481 lb | ≈ 7.23301 pdl |
| 1 dyn | = 1×10−5 N | ≡ 1 g⋅cm⁄s2 | ≈ 1.01972×10−6 kgf | ≈ 2.24809×10−6 lb | ≈ 7.23301×10−5 pdl |
| 1 kgf | = 9.80665 N | = 980665 dyn | ≡ gn × 1 kg | ≈ 2.20462 lb | ≈ 70.9316 pdl |
| 1 lb | ≈ 4.44822 N | ≈ 444822 dyn | ≈ 0.45359 kgf | ≡ gn × 1 lbm / .3048 m⁄ft | ≈ 32.1740 pdl |
| 1 pdl | ≈ 0.13825 N | ≈ 13825.5 dyn | ≈ 0.01410 kgf | ≈ 0.03108 lbf | ≡ 1 lbm⋅ft⁄s2 |
| 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 |
| Submultiples | Multiples | ||||
|---|---|---|---|---|---|
| Value | SI symbol | Name | Value | SI symbol | Name |
| 10−1 N | dN | decinewton | 101 N | daN | decanewton |
| 10−2 N | cN | centinewton | 102 N | hN | hectonewton |
| 10−3 N | mN | millinewton | 103 N | kN | kilonewton |
| 10−6 N | μN | micronewton | 106 N | MN | meganewton |
| 10−9 N | nN | nanonewton | 109 N | GN | giganewton |
| 10−12 N | pN | piconewton | 1012 N | TN | teranewton |
| 10−15 N | fN | femtonewton | 1015 N | PN | petanewton |
| 10−18 N | aN | attonewton | 1018 N | EN | exanewton |
| 10−21 N | zN | zeptonewton | 1021 N | ZN | zettanewton |
| 10−24 N | yN | yoctonewton | 1024 N | YN | yottanewton |
| 10−27 N | rN | rontonewton | 1027 N | RN | ronnanewton |
| 10−30 N | qN | quectonewton | 1030 N | QN | quettanewton |
Sources and credits
This article is adapted from the Wikipedia article “Newton (unit)”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- One Newton, illustrated (transparent background).svg by Gutten på Hemsen, CC BY-SA 4.0
- Dwire carabiner.jpg by Wikimol at English Wikipedia, CC BY-SA 3.0
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