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 It is superseded by ISO 80000-4.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):
Quantity | Unit | Remarks | |||
---|---|---|---|---|---|
Name | Symbol | Name | Symbol | Definition | |
Force | F | newton | N | 1 N = 1 kg·m/s^{2} | Unit named after Isaac Newton |
Moment of force, Torque | M, | N·m | 1 N·m = 1 kg·m^{2}/s^{2} | The unit is dimensionally equivalent to the units of energy, the joule; but the joule should not be used as an alternative for the newton metre. | |
Linear momentum | p | kg·m/s or N·s | |||
(Linear) impulse | J | N·s or kg·m/s | |||
Angular momentum | L | kg·m^{2}/s or N·m·s | |||
Mechanical energy, Work | E, W | joule | J | 1 J = 1 kg·m^{2}/s^{2} = 1 Pa·m^{3} = 1 W·s | Unit 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). |
Power | P | watt | W | 1 W = 1 J/s = 1 N·m/s = 1 kg·m^{2}/s^{3} | Unit named after James Watt. |
Pressure | p | pascal | Pa | 1 Pa = 1 N / m^{2} = 1 kg/(m·s^{2}) | Named after Blaise Pascal. |
Normal stress, Shear stress | pascal | Pa | 1 Pa = 1 N / m^{2} = 1 kg/(m·s^{2}) | Named after Blaise Pascal. | |
... |