Wikiciv - User contributions [en]

Measuring and Calibration

2026-02-21T09:36:17Z

Uncivator: Deduplicated contents and added some derived units

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.
= Useful Things to Note =
== Scientific Notation ==
Numbers can get large really fast. To shorten this so that we don't have 30 zeros floating at the end of every number, we use some basic math to describe a notation. If the number has a E(some number here), e(number), or even x10^(number), this stands in the place of x10(number).

This means that you can shorten the number 467,110,000,000 to 4.67110000000x10^11 or, roughly 4.67E11. A negative number means the same that any negative exponent means. (''See basic rules of [[Math]]'')

This means you can turn the number 0.000000846 to 8.46E-7.

== Prefixes ==
Because the previous notation can be hard to read, prefixes are available to whatever unit you want. For instance, instead of 2.53x10^-5 meters, you could say 25.3 µm which means 25.3 1 thousandths of a meter. This is much easier to picture even though it is still really small.

A common set of these prefixes go as follows:
{| class="wikitable"
|+
!name
!symbol
!meaning
!
!name
!symbol
!meaning
|-
|queta
|Q
|x1030
|
|quecto
|q
|x10-30
|-
|ronna
|R
|x1027
|
|ronto
|r
|x10-27
|-
|yotta
|Y
|x1024
|
|yocto
|y
|x10-24
|-
|zeta
|Z
|x1021
|
|zepto
|z
|x10-21
|-
|exa
|E
|x1018
|
|atto
|a
|x10-18
|-
|peta
|P
|x1015
|
|femto
|f
|x10-15
|-
|tera
|T
|x1012
|
|pico
|p
|x10-12
|-
|giga
|G
|x109
|
|nano
|n
|x10-9
|-
|mega
|M
|x106
|
|micro
|μ
|x10-6
|-
|kilo
|k
|x103
|
|mili
|m
|x10-3
|-
|hecto
|h
|x102
|
|centi
|c
|x10-2
|-
|deka
|da
|x101
|
|deci
|d
|x10-1
|}

= Base Units =
== Time: the second (s) ==
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.

There's also a "human" way to track time, but it can differ on all sorts of elements. Take this as a basic way to tell time.
{| class="wikitable"
|+Methods to track time
!Unit
!How to measure
!Equivalent to
|-
|Breath
|Inhale and exhale.
|~5 seconds
|-
|Heartbeat
|Place your second and third finger from your thumb, on your wrist or neck, every beat is a pulse.
|~1 second
|-
|Sunrise to sunset
|From the moment you can see the sun, to the moment it can't be seen anymore.
|~11-16 hours, depending on season and place
|-
|One sunrise to another sunrise
|From one sunrise to another.
|~1 day
|-
|30 sunrise to sunrise cycles
|The time it takes to see 30 sunrises.
|~1 month
|-
|One year
|About every 12 months.
|~365 days
|}
More recently the second has been redefined as a number of vibrations of the cesium element, but in everyday life this definition does not have practical use.

== Distance: the meter (m) ==
The '''meter''' is described to be roughly the length of a large walking step. Using the more precise definition of '''the distance light can travel in 1/(299,792,458) seconds.''' This comes out to be roughly 3.33564095E-9 seconds.

To approximate the meter, several methods exist:

# A second-pendulum: by suspending a mass from a length of one meter and swinging it in small oscillations, the period of the pendulum is two seconds, which means it goes from one side to the other in one second.
# A hand-based ruler: the length between the thumb and the pinky when the hand is fully extended is roughly 20cm. Therefore, five times this length is close to a meter.

Distance can be used to describe area, and volume, depending on the number of dimensions used:

* Two distances define an area, for example a one-meter by one-meter square has an area of one-meter-squared.
* Three distances define a volume, for example a one-meter by one-meter by one-meter cube has an area of one-meter-cubed.

Remarque: Yes, light has a speed, albeit incredibly fast. And as this speed is constant, it has been used to define the meter without requiring a physical object.

== Mass: the kilogram (kg) ==
When the meter has been defined it can help to get the mass unit, the '''kilogram''', which is defined as the mass of a volume of water in a 10cm x 10cm x 10cm cube.

== Electric current: the ampere (A) ==
== Temperature: the kelvin (K) ==
== Quantity: the mole (mol) ==
The '''mole''' is not really a unit as much as it is a big number which makes it easier to count bit quantities.

It is originally defined as the number of atoms contained in 12g of of carbon 12, now equal to exactly 6.02214076 × 1023.

This number is huge and not really useful in everyday life and is mainly used in chemical processes which need precision.

== Light: the candela ==

= Common derived units =
== Speed ==
Speed is defined as displacement over time, which gives it the unit "m/s" (Meter / Second)

The speed of light is defined to be exactly equal to 299,792,458 m/s

== Acceleration ==
Acceleration is the rate at which speed changes over time: '''m/s/s''' (Meter / Second / Second), most commonly notated as '''m/s2'''

== Frequency: the hertz (Hz) ==
One '''Hertz''' (Hz) is defined as '''1/s''', also notated as '''s-1'''

== Force: the netwon (N) ==
One '''Newton''' (N) is defined as the force needed to accelerate an object that has a mass of '''1 kg''' at '''1 m/s2'''. A newton is '''kg×m/s2'''

== Pressure: the pascal (Pa) ==
One '''Pascal''' (Pa) is the pressure that a force of '''1 N''' exerts on a surface of '''1 m2'''

== Energy: the joule (J) ==
One '''Joule''' (J) is the energy needed to displace a '''1 kg''' object by '''1 m''' using a force of '''1 N'''. A joule is '''N×m'''

[[Category:Maths]]
[[Category:Physics]]

Acetylene

2025-08-24T07:25:27Z

Uncivator: Added categories

'''Acetylene''' is a [[Chemical compounds|chemical compound]] with the formula C2H2 and has the structure HC≡CH.

It is a colorless and odorless gas.

= Uses =
Acetylene is highly flammable and when mixed with oxygen it gives the hottest flame of any common fuel gas, reaching over 3000 degrees celsius, making it useful for manipulating metal.

=== Steel Welding/Cutting ===
Before arc welders were invented, acetylene torches were a common method of welding steel together. They can also be used to cut steel, however their use is limited as the heat created can ruin any heat treatment that has been done on a metal.

=== Brazing ===
Brazing is the joining of two pieces of metal using a Solder of another metal. For example, Brass is sometimes used to braze the steel frames of bikes.

Acetylene can provide localized heating in order to do this method of joining metal.
= Production =
The historical method of production is the chemical reactions between calcium carbide and water.

CaC2 + 2 H2O → Ca(OH)2 + C2H2
[[Category:Chemistry]]
[[Category:Chemical compounds]]

Potash

2025-08-24T07:04:13Z

Uncivator: Added the possibility of using other materials as filters

[[File:Campfire scar 08319.JPG|thumb|Wood ash from a campfire, a major source of potash.]]
Potassium carbonate, or potash, is a carbonate salt notable for its presence in wood ash and ease of extraction therefrom. Potash has several uses and is extremely simple to produce in large quantities even with the most basic of technology, this makes it a critical primitive chemical feedstock. It may be used to produce [[lye]] by a reaction with [[Quicklime|slaked lime]] (calcium hydroxide). It is a necessary compound for the production of [[saltpeter]] from organic material and may also be used in baking as a leavening agent.

== Prerequisites ==

* [[Fire]]
* [[Wood]]
* [[Pottery]]

== Production ==
Potash is extremely simple to make, in fact it doesn't require the use of any chemical reaction, only a simple extraction. All that is needed are a piece of cloth (or any other material that can act as a filter, such as straw or grass), two containers (one wider than the other), and a lot of water.

# Cut a hole in the bottom of the wider container and stuff the filter material down in the bottom to act as a filter.
# Place the wider container over top of the other container, so that any liquid from the top drains into the bottom.
# Fill the top container with wood ash and begin pouring water through the wood ash. Continue this until the water changed from dark yellow to clear (or, light yellow if energy is being conserved).
# Boil down the liquid. This should be done in a non-metallic container (glazed pottery, glass, etc.) as potash is mildly caustic.

What is left will be relatively pure potash which can be used for any of the above mentioned processes. If higher purity is needed, potash may be recrystallized from [[methanol]] or [[ethanol]], but this is a very inconvenient process.

Hardwood ash tends to consist of about 10% potash, therefore, if one fully leaches their wood ash, they are likely to get 1 g of potash for every 10 g of wood ash. However, this is rather energy inefficient as it necessitates boiling off exponentially more water per amount of potash. This, combined with the fact that anyone rebuilding society is likely to have a massive surplus of wood ash from heating, cooking, metallurgy, etc. means that it is generally advisable to only seep out about half of that amount.

== Uses ==
Potash is an important starting point for a lot of useful chemicals, most notably [[lye]] and [[saltpeter]].

Additionally it will react with acids to produce carbon dioxide, so it can be used as a leavening agent much the same as [[baking soda]], with about a 2:1 conversion of potash to baking soda.

Potash

2025-08-24T06:57:39Z

Uncivator: Reformatted the "Production steps"

[[File:Campfire scar 08319.JPG|thumb|Wood ash from a campfire, a major source of potash.]]
Potassium carbonate, or potash, is a carbonate salt notable for its presence in wood ash and ease of extraction therefrom. Potash has several uses and is extremely simple to produce in large quantities even with the most basic of technology, this makes it a critical primitive chemical feedstock. It may be used to produce [[lye]] by a reaction with [[Quicklime|slaked lime]] (calcium hydroxide). It is a necessary compound for the production of [[saltpeter]] from organic material and may also be used in baking as a leavening agent.

== Prerequisites ==

* [[Fire]]
* [[Wood]]
* [[Pottery]]

== Production ==
Potash is extremely simple to make, in fact it doesn't require the use of any chemical reaction, only a simple extraction. All that is needed are a piece of cloth, two containers (one wider than the other), and a lot of water.

# Cut a hole in the bottom of the wider container and stuff the cloth down in the bottom to act as a filter.
# Place the wider container over top of the other container, so that any liquid from the top drains into the bottom.
# Fill the top container with wood ash and begin pouring water through the wood ash. Continue this until the water changed from dark yellow to clear (or, light yellow if energy is being conserved).
# Boil down the liquid. This should be done in a non-metallic container (glazed pottery, glass, etc.) as potash is mildly caustic.

What is left will be relatively pure potash which can be used for any of the above mentioned processes. If higher purity is needed, potash may be recrystallized from [[methanol]] or [[ethanol]], but this is a very inconvenient process.

Hardwood ash tends to consist of about 10% potash, therefore, if one fully leaches their wood ash, they are likely to get 1 g of potash for every 10 g of wood ash. However, this is rather energy inefficient as it necessitates boiling off exponentially more water per amount of potash. This, combined with the fact that anyone rebuilding society is likely to have a massive surplus of wood ash from heating, cooking, metallurgy, etc. means that it is generally advisable to only seep out about half of that amount.

== Uses ==
Potash is an important starting point for a lot of useful chemicals, most notably [[lye]] and [[saltpeter]].

Additionally it will react with acids to produce carbon dioxide, so it can be used as a leavening agent much the same as [[baking soda]], with about a 2:1 conversion of potash to baking soda.