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ISO 31-3

Updated: 2016-04-05T03:05Z

ISO 31-3 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to mechanics. It is superseded by ISO 80000-4.

Its definitions include (note boldfaced symbols mean quantity is a vector):

ForceFnewtonN1 N = 1 kg·m/s2Unit named after Isaac Newton
Moment of force, TorqueM,  \boldsymbol{\tau} N·m1 N·m = 1 kg·m2/s2The unit is dimensionally equivalent to the units of energy, the joule; but the joule should not be used as an alternate for the newton metre.
Linear momentumpkg·m/s or N·s
(Linear) impulseJN·s or kg·m/s
Angular momentumLkg·m2/s or N·m·s
Mechanical energy, WorkE, WjouleJ1 J = 1 kg·m2/s2 = 1 Pa·m3 = 1 W·sUnit named after James Joule. The joule is dimensionally equivalent to the units of torque and moment of force but should be used in preference to the newton metre (N·m).
PowerPwattW1 W = 1 J/s = 1 N·m/s = 1 kg·m2/s3Unit named after James Watt.
PressureppascalPa1 Pa = 1 N / m2 = 1 kg/(m·s2)Named after Blaise Pascal.
Normal stress, Shear stress\sigma, \tau pascalPa1 Pa = 1 N / m2 = 1 kg/(m·s2)Named after Blaise Pascal.

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