diy solar

diy solar

Impress your friends by using correct units and abbreviations

It is amazing how much real engineering can be accomplished with imaginary numbers.
In classwork, we used Euler's identity in integral calculus equations to determine magnitude and phase, waves propagating in lossy mediums, etc.
I try to solve my resistor, capacitor, inductor problems with ancient Greek (Pythagorean Theorem) math when possible (KISS).

Where there is a duality between electrical and mechanical or thermal engineering, I'm able to dabble in those fields as well. But forget about Ryleigh-Taylor instability, I'll leave that to someone else. I am aware of a vibration isolator design project, will see if I can evaluate it like I would a Butterworth or other multi-stage filter.
 
The following are common units and their abbreviations. Note that unit abbreviations are case-sensitive. While some units can be understood when written incorrectly, some have a completely different meaning if the wrong case is used. Avoid any possible confusion or ambiguity and use the correct case.

A - amps, a unit of current. Named after André-Marie Ampère.
...
You forgot the most useful units to really impress your friends !
m - Meter, a unit of distance in the generally admitted International System of units
g - Gramm, a unit of weight in the generally admitted International System of units
°k - Kelvin, a unit of temperature in the generally admitted International System of units, also °C, shifted by 273 °K into common tempeatures on earth.
;)
 
You forgot the most useful units to really impress your friends !
m - Meter, a unit of distance in the generally admitted International System of units
g - Gramm, a unit of weight in the generally admitted International System of units
°k - Kelvin, a unit of temperature in the generally admitted International System of units, also °C, shifted by 273 °K into common tempeatures on earth.
;)

Surely you mean "metre", "gram" (or "gramme") and "K" (there's no degree symbol with it) ;)

I know, I know, different spellings on your side of The Pond :)
 
g - Gramm, a unit of weight in the generally admitted International System of units
A gram, g, is a unit of mass, not weight. Weight is a force.

The gram ceased to be the base SI unit of mass in 1960 and was replaced by the kilogram, kg, while the gram became a derived unit of the kg.

°k - Kelvin
There is no ° symbol when expressing a temperature in units of kelvin and it uses an upper case K.

e.g. it's 273 K, not 273 °K and not 273 °k.

The world kelvin is also not capitalised, the same as "metre", "watt", "kilogram" and "gram" except when used in a title or at the start of a sentence.
 
The gram ceased to be the base SI unit of mass in 1960 and was replaced by the kilogram, kg, while the gram became a derived unit of the kg.
The world kelvin is also not capitalised, the same as "metre", "watt", "kilogram" and "gram" except when used in a title or at the start of a sentence.
Ok, you and Crossy win!
(y)
I still feel more comfortable using them with the wrong grammar, than to keep using imperial units, remnants of a medieval age.
 
Ok, you and Crossy win!
(y)
I still feel more comfortable using them with the wrong grammar, than to keep using imperial units, remnants of a medieval age.

Aren't they now called "US customary units" and are subtly different from "imperial"?

We Brits use an eclectic mix of metric (fuel in litres) and imperial (distances in miles) etc. etc. and 8'x 4' plasterboard is actually 1.2m x 2.4m. I think we do it just to confuse the French!

I couldn't get replacement doors for our place in the UK, turns out our doors were "metric" and the standard 6'6" x 2'6" doors were just the wrong shape.
 
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Aren't they now called "US customary units" and are subtly different from "imperial"?

We Brits use an eclectic mix of metric (fuel in litres) and imperial (distances in miles) etc. etc. I think we do it just to confuse the French!

I couldn't get replacement doors for our place in the UK, turns out our doors were "metric" and the standard 6'6" x 2'6" doors were just the wrong shape.
You are not only confusing the French.
Enjoy your Brexit !...
 
using imperial units, remnants of a medieval age
I could write three pages about traditional units of measure and how they were derived. Why they fractionally divide in ways that create comfort, how that feet and inches scale out to the Golden Mean and how - inexplicably - Vesuvius and Michelangelo demonstrated ratios in nature that scale out in quarters, eighths and fifths.

That’s a weird thing in post modern culture- so many folks think things are remnants of a poorly developed period of the past - medieval- yet have no knowledge of how advanced the past was. “The Minds” of those derelict simpleton times calculated things like the presence of unseen planets and created order of that which was seen with math, not computers.

That we arrived at 10-base math isn’t surprising. That we insist on using it as measure for volume or for furniture design is surprising, since “we” - by nature- see things in halves, quarters, fifths, twelfths because everything in nature works that way.
Remnants of the past are often remnants of intelligence.
 
because everything in nature works that way
Some things, not everything.

Some life follows prime number patterns as a result of evolutionary optimisation pressures (e.g. the breeding cycles of cicadas are typically in prime numbers of years so as to minimise chances of competing colonies appearing in the same year).

Natural growth and decay patterns in life (and many parts of the natural physical world) follow a natural exponent e, and the emergence of π of course should be obvious in nature - there's a reason it pops up in so many physics formulae.

Other life tends to display the golden ratio, φ, or other similar irrationals like the silver ratio and we see this in the way Fibonacci numbers pop up in all sorts of places, e.g. the structure of seed placements on flowers, or leaves around a stalk or the way gastropods shells grow. Even the manner in which hereditary traits work is related to these numbers. Indeed some electrical circuits such as resistance ladders follow such Fibonacci patterns.

Then of course much of nature works in chaotic ways and a lot of nature is best described by fractals.
 
That we arrived at 10-base math isn’t surprising. That we insist on using it as measure for volume or for furniture design is surprising, since “we” - by nature- see things in halves, quarters, fifths, twelfths because everything in nature works that way.
???
I sometimes think of how the world would have been, if humans had 8 or 12 fingers. Probably better...
But, pardon me, only US citizens think in fractions.
It is just unnatural to use a 10-base math together with fractional measurement units.
A regular bottle of wine is 75cl, nobody in Europe would call it a 3/4l bottle.
 
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I once worked for a company that shall forever remain nameless, but we were designing safety critical systems used to move large numbers of people...

Anyhow, the Chief quality control honcho once told me that we only check documents and reports for correct spelling, font, width of margins, and that documents absolutely must conform to the official template. We never check facts, figures, or actual content.

So total nonsense gets a pass. But woe betide anyone that dares to submit something with a slightly displaced heading.
You must have worked for the the Washington Post! ?
 
A gram, g, is a unit of mass, not weight. Weight is a force.

The gram ceased to be the base SI unit of mass in 1960 and was replaced by the kilogram, kg, while the gram became a derived unit of the kg.


There is no ° symbol when expressing a temperature in units of kelvin and it uses an upper case K.

e.g. it's 273 K, not 273 °K and not 273 °k.

The world kelvin is also not capitalised, the same as "metre", "watt", "kilogram" and "gram" except when used in a title or at the start of a sentence.
Oh so close…

You forgot Celsius as in degrees Celsius which is always capitalized.
 
But, pardon me, only US citizens think in fractions.
It is just unnatural to use a 10-base math together with fractional measurement units.
A regular bottle of wine is 75cl, nobody in Europe would call it a 3/4l bottle.
You are thinking empirically, logically, computational. You are missing the point. You are thinking it’s merely a matter of computational efficiency to be 10-based:
humans had 8 or 12 fingers.
Fingers have nothing to do with how ‘we’ arrived at 10-base numbering and math. We arrived there because it creates computational possibilities in a linearly predictable and repeatable fashion. (Humans do have 8 fingers btw)

This guy:
Natural growth and decay patterns in life (and many parts of the natural physical world) follow a natural exponent e, and the emergence of π of course should be obvious in nature - there's a reason it pops up in so many physics formulae.

Other life tends to display the golden ratio, φ, or other similar irrationals like the silver ratio and we see this in the way Fibonacci numbers pop up in all sorts of places, e.g. the structure of seed placements on flowers, or leaves around a stalk or the way gastropods shells grow.
He understands that math isn’t made up of merely a 10-based place-to-value system. It’s the reason some beautifully crafted architecture feels ‘sterile’ or uncomfortable if not somehow cold, while others even those in a similar style or discipline feel relaxing and/or inviting and welcoming.

It’s not about fractions (everything is divisible to fractions and multiples) but about the ratios of the fractions and how they appear in nature- and how they affect us emotionally.
 
This thread is like taking an ADVANCED ABSTRACT COLLEGE course. I don't know what the course title would be.
So far I am getting a "C". ?‍♂️
 
You forgot Celsius as in degrees Celsius which is always capitalized.
Indeed, although I didn't forget it, I just didn't mention it. Like I didn't mention dozens of other units.

There are style guides for this stuff. While Wikipedia is a reference to always take care with, its article on this is pretty good and it provides links to the SI style guides.

As to units themselves, there are only seven base SI units. All other units are derived from them:
second
metre
kilogram
ampere
kelvin
mole
candela

That's it.
 
see things in halves, quarters, fifths, twelfths because everything in nature works that way.
Bananas are made in thirds....

A regular bottle of wine is 75cl, nobody in Europe would call it a 3/4l bottle.
Over here liquor and wine is now sold in 750ml (not 75cl) bottles (~25.4 oz), which is conveniently close to "a fifth" or 1/5 U.S. gallon (25.6 oz), which was the standard size before they realized they could swindle us out of ~0.2 oz of spirits by simply relabeling the bottle in metric and charging the same price.

Most U.S. folks haven't the slightest clue how much volume a centiliter is. Heck, they barely recognize milliliters or liters.

To heck with units; when do we get to impress our friends by using proper grammar and spelling?
Its/It's
Their/They're/There
Than/Then
All drive me daffy when I see them misused. I even see these misused in magazines and newspapers now since nobody cares to afford proofreaders any more.
 
Bananas are made in thirds
a quarter of 12ths ;)

Drawers are made in thirds, or are a progression, or a scaled factored division. Adding drawer size progression by “inches” or “centimeters” does not “look right” whereas a geometric progression: does.
I don’t know if 18th century chairmakers thought about ratios and emotional response or not, but it’s amazing to me how often they got it ‘right!
 
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