Measuring and Calibration: Difference between revisions
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The '''International System of Units (SI)''' is the modern metric system used globally for precise measurement. It defines seven base units (meter, kilogram, second, ampere, kelvin, mole, and candela) from which all other units are derived. These units are '''universal, coherent, and based on fundamental physical constants'''. By adopting SI units, a post-collapse society can '''restore scientific progress, fair trade, and efficient resource management''', laying the groundwork for sustainable development. | |||
== Distance: the metre == | |||
The '''meter''' is described to be roughly the length of a walking step, using the more precise definition of '''one ten-millionth of the distance from the equator to the North Pole''' of the Earth globe. | |||
To approximate the meter, several methods exist: | |||
# a second-pendulum: by suspending a mass from a length of one meter | |||
== Mass: the kilogram == | |||
== Time: the second == | |||
The '''second''' is historically defined through the '''duration of the day'''. One day is divided into 24 hours, which are first divided into 60 minutes which are in turn divided into 60 second each. | |||
* 1 day = 24 hours, 1 hour = 60 minutes, 1 minute = 60 seconds. | |||
More recently the second has been redefined as a number of vibrations of the caesium element, but in everyday life this definition does not have practical use. | |||
== Electric current: the ampere == | |||
== Temperature: the kelvin == | |||
== Quantity: the mole == | |||
== Light: the candela == | |||
== Useful sub-units == | |||
=== Frequency: number of occurrences per second === | |||
=== Force: mass x displacement over time === | |||
=== Pressure: force over surface === | |||
Energye | |||
[[Category:Maths]] | [[Category:Maths]] | ||
[[Category:Physics]] | [[Category:Physics]] | ||
Revision as of 18:16, 10 May 2025
The International System of Units (SI) is the modern metric system used globally for precise measurement. It defines seven base units (meter, kilogram, second, ampere, kelvin, mole, and candela) from which all other units are derived. These units are universal, coherent, and based on fundamental physical constants. By adopting SI units, a post-collapse society can restore scientific progress, fair trade, and efficient resource management, laying the groundwork for sustainable development.
Distance: the metre
The meter is described to be roughly the length of a walking step, using the more precise definition of one ten-millionth of the distance from the equator to the North Pole of the Earth globe.
To approximate the meter, several methods exist:
- a second-pendulum: by suspending a mass from a length of one meter
Mass: the kilogram
Time: the second
The second is historically defined through the duration of the day. One day is divided into 24 hours, which are first divided into 60 minutes which are in turn divided into 60 second each.
- 1 day = 24 hours, 1 hour = 60 minutes, 1 minute = 60 seconds.
More recently the second has been redefined as a number of vibrations of the caesium element, but in everyday life this definition does not have practical use.
Electric current: the ampere
Temperature: the kelvin
Quantity: the mole
Light: the candela
Useful sub-units
Frequency: number of occurrences per second
Force: mass x displacement over time
Pressure: force over surface
Energye