upsilon
NUMBERS π AND e
π = 3.141 592 653 589 793
e = 2.718 281 828 459 045
log10 e = 0.434 294 481 903
loge 10 = 2.302 585 092 994
Units are labels that are used to distinguish one type of measurable quantity from other types. Length, mass, and time are distinctly different physical quantities, and therefore have different unit names, such as meters, kilograms and seconds. We use several systems of units, including the metric (SI), the English (or U.S. customary units), and a number of others, which are of mainly historical interest.
This part of the book contains the following:
• International System of Units
• Metric Units of Measurement
• U.S. Units of Measurement
• Units of Measure in Precious Metals
• Tables of Equivalents
The International System of Units, abbreviated as SI, is the modernized version of the metric system established by international agreement.
| Quantity | Name | Symbol |
| length | meter | m |
| mass | kilogram | kg |
| time | second | s |
| electric current | ampere | A |
| thermodynamic temperature | kelvin | K |
| amount of a substance | mole | mol |
| Quantity | Name | Symbol |
| area | square meter | m2 |
| volume | cubic meter | m3 |
| speed, velocity | meter per second | m/s |
| acceleration | meter per second squared | m/s2 |
| wave number | reciprocal meter | m−1 |
| mass density | kilogram per cubic meter | kg/m3 |
| specific volume | cubic meter per kilogram | m3/kg |
| current density | ampere per square meter | A/m2 |
| magnetic field strength | ampere per meter | A/m |
| amount-of-substance concentration | mol per cubic meter | mol/m3 |
| luminance | candela per square meter | cd/m2 |
| mass fraction | kilogram per kilogram | kg/kg |
3. SI Derived Units with Special Names and Symbols
| Quantity | Name | Symbol |
| plane angle | radian | rad |
| solid angle | steradian | sr |
| frequency | hertz | Hz |
| force | newton | N |
| pressure, stress | pascal | Pa |
| energy, work, quantity of heat | joule | J |
| power, radiant flux | watt | W |
| electric charge, quantity of electricity | coulomb | C |
| electric potential difference | volt | V |
| capacitance | farad | F |
| electric resistance | ohm | Ω |
| electric conductance | siemens | S |
| magnetic flux | weber | Wb |
| magnetic flux density | tesla | T |
| inductance | henry |
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