Newton
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The newton (symbol: N) is the SI derived unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics.
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The newton is the amount of force that is required to accelerate a kilogram of mass at a rate of one meter per second squared. Algebraically:
- 1 N is the force of Earth's gravity on an object with a mass of about 102 g (1⁄9.8 kg) (such as a small apple).
- On Earth's surface, a mass of 1 kg exerts a force of approximately 9.81 N [down] (or 1 kgf). The approximation of 1 kg corresponding to 10 N is sometimes used as a rule of thumb in everyday life and in engineering.
- The force of Earth's gravity on a human being with a mass of 70 kg is approximately 687 N.
- The scalar product of force and distance (N·m)— a force of 1 N exerted over a distance of 1 m— is one joule, the SI unit of energy.
- Because a newton is a small amount of force, it is common to see forces expressed in kilonewtons or kN, where 1 kN = 1 000 N.
- A metric tonne (1 000 kg) exerts a force of 9.8 kN (or 1 000 kgf) under standard gravity conditions on Earth.
| newton (SI unit) |
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 |
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The value of gn as used in the official definition of the kilogram-force is used here for all gravitational units.
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| This SI unit is named after Isaac Newton. As for all SI units whose names are derived from the proper name of a person, the first letter of its symbol is uppercase (N). But when an SI unit is spelled out, it should always be written in lowercase (newton), unless it begins a sentence or is the name "degree Celsius".
— Based on The International System of Units, section 5.2.
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- Joule, the SI unit of energy, equivalent to 1 newton exerted over a distance of 1 metre.
- Pascal, the SI unit of pressure, equivalent to 1 newton acting on an area of 1 square metre.
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