newton | |
---|---|
General information | |
Unit system | SI |
Unit of | force |
Symbol | N |
Named after | 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). 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.
A newton is defined as 1 kg⋅m/s2 (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 one metre per second every second. [2]
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. [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 Isaac Newton . As with every SI unit named for 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: [5] where represents the mass of the object undergoing an acceleration . 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, = 9.80665 m/s2), a kilogram mass exerts a force of about 9.81 N.
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
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 (9.80665 m/s2) as used in the official definition of the kilogram-force is used here for all gravitational units. |
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 |
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 |
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 |
The kilogram is the base unit of mass in the International System of Units (SI), having the unit symbol kg. 'Kilogram' means 'one thousand grams' and is colloquially abbreviated to kilo.
The International System of Units, internationally known by the abbreviation SI, is the modern form of the metric system and the world's most widely used system of measurement. Coordinated by the International Bureau of Weights and Measures it is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce.
In science and engineering, the weight of an object is a quantity associated with the gravitational force exerted on the object by other objects in its environment, although there is some variation and debate as to the exact definition.
The metric system is a decimal-based system of measurement. The current international standard for the metric system is the International System of Units, in which all units can be expressed in terms of seven base units: the metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), and candela (cd). These can be made into larger or smaller units with the use of metric prefixes.
The pascal is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m2). It is also equivalent to 10 barye in the CGS system. Common multiple units of the pascal are the hectopascal, which is equal to one millibar, and the kilopascal, which is equal to one centibar.
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The kilogram-force, or kilopond, is a non-standard gravitational metric unit of force. It is not accepted for use with the International System of Units (SI) and is deprecated for most uses. The kilogram-force is equal to the magnitude of the force exerted on one kilogram of mass in a 9.80665 m/s2 gravitational field. That is, it is the weight of a kilogram under standard gravity. One kilogram-force is defined as 9.80665 N. Similarly, a gram-force is 9.80665 mN, and a milligram-force is 9.80665 μN.
The standard atmosphere is a unit of pressure defined as 101325 Pa. It is sometimes used as a reference pressure or standard pressure. It is approximately equal to Earth's average atmospheric pressure at sea level.
The metre per second squared is the unit of acceleration in the International System of Units (SI). As a derived unit, it is composed from the SI base units of length, the metre, and time, the second. Its symbol is written in several forms as m/s2, m·s−2 or ms−2, , or less commonly, as (m/s)/s.
The newton-second is the unit of impulse in the International System of Units (SI). It is dimensionally equivalent to the momentum unit kilogram-metre per second (kg⋅m/s). One newton-second corresponds to a one-newton force applied for one second.
A kilogram-force per square centimetre (kgf/cm2), often just kilogram per square centimetre (kg/cm2), or kilopond per square centimetre (kp/cm2) is a deprecated unit of pressure using metric units. It is not a part of the International System of Units (SI), the modern metric system. 1 kgf/cm2 equals 98.0665 kPa (kilopascals) or 0.980665 bar—2% less than a bar. It is also known as a technical atmosphere.
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