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SI units system Tolerances / Tables / Standards

SI is the modern system of units for as the metric system. SI is used in all ar- units, Additional units, Prefixes. The fig-
measurement, accepted and used world eas of science, technology and trade and ures given in the conversion tables are
wide. It is used in all areas of international is applied in the same way world wide. rounded up to 3 or 4 digits.
standards and is commonly referred to SI is built of: Base units, Supplementary

1. Basic units of the SI system

Quantity Name Symbol
Length meter m
Mass kilogram kg
Time second s
Electric current ampere A
Termodynamic temperature kelvin K
Luminous intensity candela dc
Amount of substance mole mol
Plan angle radian rad
Solid angle steradian sr

2. Derived SI units
Quantity Name Symbol Defining equation
Frequency hertz Hz 1 Hz = 1 s = 1/s
–1
Force newton N 1 N = 1 kg · m/s 2
Pressure and mechanical stress pascal Pa 1 Pa = 1 N/m 2
Work (energy, heat) joule J 1 J = 1 N · m = 1 W · s
Power, energy flow, heat flow watt W 1 W = 1 N · m/s = J/s
Electrical charge, quantity of electricity coulomb C 1 C = 1 A · s
Plectrical potential, potential, difference voltage volt V 1 V = 1 W/A
Electric capacitance farad F 1 F = 1 A · s/V
Impedance ohm Ω 1 Ω = 1 V/A
Electrical conductivity siemens S 1 S = 1 Ω = 1 A/V
–1
Magnetic flux weber Wb 1 WB = 1 V · s
Magnetic flux density tesla T 1 T = 1 Wb/m 2
Industance henry H 1 H = 1 Wb/A = 1 V · s/A
Luminous flux lumen lm 1 lm = 1 cd · sr
Illumination lux lx 1 lx = 1 lm/m 5

Conversion tables

Conversion table for units of force
N p kp dyn
1 Newton = 1 N 1 102 0,102 10 5
1 pond = 1 p 9,81 · 10 –3 1 10 –3 981
1 Kilopond = 1 kp 9,81 1000 1 9,81 · 10 5
1 dyn 10 –5 1,02 · 10 –3 1,02 · 10 –6 1

Conversion table for units of mechanical stress
Pa N/mm 2 kp/cm 2 kp/mm 2
1 Pa = 1 N/m 2 1 10 –6 1,02 · 10 –5 1,02 · 10 –7
1 N/mm = 1 MPa 10 6 1 10,2 0,102
2
1 kp/cm = 1 at 9,81 · 10 4 9,81 · 10 –2 1 10 –2
2
1 kp/mm 2 9,81 · 10 6 9,81 100 1