Units of measurement::Force
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Units of measurement
The SI unit of force is the newton (symbol N), which is the force required to accelerate a one kilogram mass at a rate of one meter per second squared, or kg·m·s^{−2}.<ref name= metric_units>{{#invoke:citation/CS1|citation
|CitationClass=book
}}</ref> The corresponding CGS unit is the dyne, the force required to accelerate a one gram mass by one centimeter per second squared, or g·cm·s^{−2}. A newton is thus equal to 100,000 dynes.
The gravitational foot-pound-second English unit of force is the pound-force (lbf), defined as the force exerted by gravity on a pound-mass in the standard gravitational field of 9.80665 m·s^{−2}.<ref name=metric_units/> The pound-force provides an alternative unit of mass: one slug is the mass that will accelerate by one foot per second squared when acted on by one pound-force.<ref name=metric_units/>
An alternative unit of force in a different foot-pound-second system, the absolute fps system, is the poundal, defined as the force required to accelerate a one-pound mass at a rate of one foot per second squared.<ref name=metric_units/> The units of slug and poundal are designed to avoid a constant of proportionality in Newton's Second Law.
The pound-force has a metric counterpart, less commonly used than the newton: the kilogram-force (kgf) (sometimes kilopond), is the force exerted by standard gravity on one kilogram of mass.<ref name= metric_units/> The kilogram-force leads to an alternate, but rarely used unit of mass: the metric slug (sometimes mug or hyl) is that mass that accelerates at 1 m·s^{−2} when subjected to a force of 1 kgf. The kilogram-force is not a part of the modern SI system, and is generally deprecated; however it still sees use for some purposes as expressing aircraft weight, jet thrust, bicycle spoke tension, torque wrench settings and engine output torque. Other arcane units of force include the sthène, which is equivalent to 1000 N, and the kip, which is equivalent to 1000 lbf.
navbar}} | newton (SI unit) |
dyne | kilogram-force, kilopond |
pound-force | poundal |
---|---|---|---|---|---|
1 N | ≡ 1 kg⋅m/s^{2} | = 10^{5} dyn | ≈ 0.10197 kp | ≈ 0.22481 lb_{F} | ≈ 7.2330 pdl |
1 dyn | = 10^{−5} N | ≡ 1 g⋅cm/s^{2} | ≈ 1.0197 × 10^{−6} kp | ≈ 2.2481 × 10^{−6} lb_{F} | ≈ 7.2330 × 10^{−5} pdl |
1 kp | = 9.80665 N | = 980665 dyn | ≡ g_{n}⋅(1 kg) | ≈ 2.2046 lb_{F} | ≈ 70.932 pdl |
1 lb_{F} | ≈ 4.448222 N | ≈ 444822 dyn | ≈ 0.45359 kp | ≡ g_{n}⋅(1 lb) | ≈ 32.174 pdl |
1 pdl | ≈ 0.138255 N | ≈ 13825 dyn | ≈ 0.014098 kp | ≈ 0.031081 lb_{F} | ≡ 1 lb⋅ft/s^{2} |
The value of g_{n} as used in the official definition of the kilogram-force is used here for all gravitational units. |
See also Ton-force.
Force sections
Intro Development of the concept Pre-Newtonian concepts Newtonian mechanics Special theory of relativity Descriptions Fundamental forces Non-fundamental forces Rotations and torque Kinematic integrals Potential energy Units of measurement Force measurement See also Notes References Further reading External links
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