In Australia, centimetres, metres and kilometres are the only measurements in general usage here (ugh I hate the spell checker here, it keeps chucking a wobbly about our 'proper' spellings lol) it's re- not er...
Units moderator. There should be a units moderator assigned.
- Thread starter l00semarble
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OffGridForGood
Catch, make or grow everything you can.
I work with architectural and engineering drawings every day.
Elevations are all in xxx.xxx meters and three decimals of a meter above mean sealevel.
95% of all measured drawings I see are in mm - even a mine building that was 160,000 mm long is shown in mm.
if we had a mix of cm and mm on plans it wouldn't be hard to make a mistake. But meters & mm there is no way to make a mistake.
if we did try to use cm, the measure is too rough, for industry, you would still need to add a decimal "36.8cm" (the spacing blocks between joists and trusses LOL)
Elevations are all in xxx.xxx meters and three decimals of a meter above mean sealevel.
95% of all measured drawings I see are in mm - even a mine building that was 160,000 mm long is shown in mm.
if we had a mix of cm and mm on plans it wouldn't be hard to make a mistake. But meters & mm there is no way to make a mistake.
if we did try to use cm, the measure is too rough, for industry, you would still need to add a decimal "36.8cm" (the spacing blocks between joists and trusses LOL)
McKravitts
Solar Enthusiast
- Joined
- Sep 8, 2022
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Considering that ever mission requires a few unexpected ΔV burns, space flight is not an exact science.3.14159265357 is about all I remember. Apparently I'm a couple digit's short of NASA's requirements, and my brain has suffered some parity errors.
3.141592653589793
How Many Decimals of Pi Do We Really Need? - Edu News | NASA/JPL Edu
While world record holders may have memorized more than 70,000 digits of pi, a JPL engineer explains why you really only need a tiny fraction of that for most calculations – even at NASA.www.jpl.nasa.gov
A high percentage of flyby's (gravity assists) have unexplained anomolies and require an extra ΔV burn after the flyby.
Other than math, I am not aware of any science that requires a highly accurate value of PI.
Warpspeed
Solar Wizard
And how do you measure mean sea level to 1mm of accuracy, with waves and tides and so on ?
Someone could pee into the ocean, and mess up all your figures.
OffGridForGood
Catch, make or grow everything you can.
Well if ya drink too much...I guess!!
Warpspeed
Solar Wizard
Drinking is never the problem.
Its peeing that causes the anomaly.
OffGridForGood
Catch, make or grow everything you can.
and what causes all that pee ... well in my own experience anyway!
Tulex
Solar Wizard
3.14 is close enough for non technical stuff. Most people can remember that.
I did say 'in general public use'...
Yes in the trades we use mm/m/km (my property for example is measured in metres on the council plans, but its pretty small for the area at only 16 hectares (40 acres), many of the farms around here have their boundaries in km with decimal points eg 5.345km is accurate down to the metre- but in surveying they go down to the mm here, which makes the council plans for a big property have ridiculously large numbers on them, as they will literally show a multi km boundary length in mm- see we got stupid bureaucrats as well lol)- our plans for solar gridtie installs use mm for example
OffGridForGood
Catch, make or grow everything you can.
Lets see!
Google says the area of the worlds' oceans is approx 361,000,000 sqkm
so to raise mean sea level 1mm you need to pee ...361,000,000,000 cubic meters (or 361,000,000,000,000 litres)
I think you drink to much!
OffGridForGood
Catch, make or grow everything you can.
Let's check!
you are building a silo 30 feet in diameter x 1 foot wall thickness x 30 feet tall.
The foreman asks you to order the concrete to fill the form, but don't get too much (it is expensive) or be short!
you use 3.14 x 30 x 1 x 30 and get 2,826 cuft of concrete.
the 'actual' volume is 3.1415926 x 30 x1 x30 = 2,827.43
and you are only short 1.43 cuft of concrete.
{and since it is sold in cu yds, you actually needed 104.7 and rounded up to 105 cyds and had enough either way!}
Especially if you've had a few Darwin stubbies...
(for the non Aussies- its a beer bottle (stubby as opposed to a longneck)- which holds 2.25 litres (thats 76.1 US ounces or 79.2 UK ounces)
Darwin Stubby wiki
OffGridForGood
Catch, make or grow everything you can.
Like I said!
Warpspeed
Solar Wizard
Beer causes climate change.
Warpspeed
Solar Wizard
Every drop counts.
And its not just me !!!!!
There are now almost eight billion other people peeing into the ocean as well.
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Hedges
I See Electromagnetic Fields!
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- 20,689
...
How do you measure the temperature of the Earth to 1/10th of a degree?
From Death Valley to Antarctica, from 4th of July to Christmas ...
Warpspeed
Solar Wizard
Easy.
With a thermometer with 1/10 degree resolution.
But I have yet to see a marine acoustic fathometer with 1mm resolution.
Helmsman to captain:
"Aye Captain, 183.1473 fathoms under the Keel to seven digit resolution"
Architect to builder:
Revise those plans, an approaching asteroid has modified sea level by 2mm in your area.
That concrete you just laid, will need to be removed and replaced.
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wattmatters
Solar Wizard
Just travel. Go to a high altitude place near the equator and you'll weigh less.
wattmatters
Solar Wizard
They use designated tide stations and laser altimeters from space combined with special satellites used for gathering average ocean levels on an ongoing basis.
Warpspeed
Solar Wizard
I know how it works, I spent two years living at weather stations in the Antarctic that also monitored sea levels.
But I find it amusing that you can average out a more or less random and confused twenty foot ocean swell to +/- 1mm of accuracy.
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