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Torque ; system unit unit-code symbol or abbrev. notes sample default conversion combination output units Industrial: SI: newton-metre: Nm N⋅m Triple combinations are also possible. See the full list. 1.0 N⋅m (0.74 lbf⋅ft) Nm kg.m; Nm lb.ft; Non-SI metric: kilogram metre: kg.m kg⋅m 1.0 kg⋅m (9.8 N⋅m; 7.2 lb⋅ft) kg.m Nm; kg.m lb.ft ...
A pound-foot (lb⋅ft), abbreviated from pound-force foot (lbf · ft), is a unit of torque representing one pound of force acting at a perpendicular distance of one foot from a pivot point. [2] Conversely one foot pound-force (ft · lbf) is the moment about an axis that applies one pound-force at a radius of one foot.
The amount of torque needed to cause any given angular acceleration (the rate of change in angular velocity) is proportional to the moment of inertia of the body. Moments of inertia may be expressed in units of kilogram metre squared (kg·m 2) in SI units and pound-foot-second squared (lbf·ft·s 2) in imperial or US units.
Moved distance per unit time: the first time derivative of position m/s L T −1: vector Wavevector: k →: Repetency or spatial frequency vector: the number of cycles per unit distance m −1: L −1: vector Weight: w: Gravitational force on an object newton (N = kg⋅m/s 2) L M T −2: vector
An example is the calculation of the rotational kinetic energy of the Earth. As the Earth has a sidereal rotation period of 23.93 hours, it has an angular velocity of 7.29 × 10 −5 rad·s −1. [2] The Earth has a moment of inertia, I = 8.04 × 10 37 kg·m 2. [3] Therefore, it has a rotational kinetic energy of 2.14 × 10 29 J.
Torque has the dimension of force times distance, symbolically T −2 L 2 M and those fundamental dimensions are the same as that for energy or work. Official SI literature indicates newton-metre, is properly denoted N⋅m, as the unit for torque; although this is dimensionally equivalent to the joule, which is not used for torque.
The moment of inertia, denoted by I, measures the extent to which an object resists rotational acceleration about a particular axis; it is the rotational analogue to mass (which determines an object's resistance to linear acceleration). The moments of inertia of a mass have units of dimension ML 2 ([mass] × [length] 2).
After converting to SI units, Cavendish's value for the Earth's density, 5.448 g cm −3, gives G = 6.74 × 10 −11 m 3 kg –1 s −2, [24] which differs by only 1% from the 2014 CODATA value of 6.67408 × 10 −11 m 3 kg −1 s −2. [25] Today, physicists often use units where the gravitational constant takes a different form.