In a parallel universe, someone is memeing about how teachers waste our time on useless stuff and never taught us to convert between units.
this post was submitted on 13 Aug 2024
691 points (97.9% liked)
Lemmy Shitpost
26951 readers
5005 users here now
Welcome to Lemmy Shitpost. Here you can shitpost to your hearts content.
Anything and everything goes. Memes, Jokes, Vents and Banter. Though we still have to comply with lemmy.world instance rules. So behave!
Rules:
1. Be Respectful
Refrain from using harmful language pertaining to a protected characteristic: e.g. race, gender, sexuality, disability or religion.
Refrain from being argumentative when responding or commenting to posts/replies. Personal attacks are not welcome here.
...
2. No Illegal Content
Content that violates the law. Any post/comment found to be in breach of common law will be removed and given to the authorities if required.
That means:
-No promoting violence/threats against any individuals
-No CSA content or Revenge Porn
-No sharing private/personal information (Doxxing)
...
3. No Spam
Posting the same post, no matter the intent is against the rules.
-If you have posted content, please refrain from re-posting said content within this community.
-Do not spam posts with intent to harass, annoy, bully, advertise, scam or harm this community.
-No posting Scams/Advertisements/Phishing Links/IP Grabbers
-No Bots, Bots will be banned from the community.
...
4. No Porn/Explicit
Content
-Do not post explicit content. Lemmy.World is not the instance for NSFW content.
-Do not post Gore or Shock Content.
...
5. No Enciting Harassment,
Brigading, Doxxing or Witch Hunts
-Do not Brigade other Communities
-No calls to action against other communities/users within Lemmy or outside of Lemmy.
-No Witch Hunts against users/communities.
-No content that harasses members within or outside of the community.
...
6. NSFW should be behind NSFW tags.
-Content that is NSFW should be behind NSFW tags.
-Content that might be distressing should be kept behind NSFW tags.
...
If you see content that is a breach of the rules, please flag and report the comment and a moderator will take action where they can.
Also check out:
Partnered Communities:
1.Memes
10.LinuxMemes (Linux themed memes)
Reach out to
All communities included on the sidebar are to be made in compliance with the instance rules. Striker
founded 1 year ago
MODERATORS
This is actually pretty important to being able to solve engineering problems in the real world. Invariably, every little sub industry has its own cursed unit system. And dimensional analysis is great for solving real problems on its own.
And if you get to a high enough physics level, they start setting hbar = c = 1 or G = c = 1, and you never have to worry about it again.
I'm the mean time, it's worthwhile to learn the trick to do this stuff fast-ish.
I would like to introduce everyone to this video about cursed unit (youtube link warning)
kWh has an intuitive reason. Watts are so small that you'd always calculate consumption in MJ and whatnot, and seconds are so short that you'd always be expressing time in ks. Using kWh will reduce the numbers to useful ranges and makes cancelling M and k unnecessary.
Yeah, he elaborated it in his second video about the cursed unit that cursed ≠ useless.
load more comments
(1 replies)
I dislike that my highschool never once gave me the concept that units can simply be treated like constants to be cancelled out.
I used to do the conversions for each variable before putting them in the equation like a fool.
Now I'm slapping all of the conversions alongside the original values/units in a single expression like god intended.
Just divide by 3.6
Example:
10 km /h * 1000 m / km = 10,000 m /h
10,000 m/h * 1h/3600s = 10,000/ 3,6000 m/s = 10/3.6 m/s
Shit like this is why we need metric time.
don't speak like the french
Shit like this is why metric needs to be replaced with a base12 system. Base10 is for children who still count on their fingers.
Dozenal for the win !!! It will never happen though, but dreaming is allowed
If at could start at blank slate then base 12 would make a better foundation, but base 10 is far too ingrained into every aspect of our life. It's much easier to convert time into base 10 than it would be to convert the world into base 12.
I used to do it this way in highschool, but could never remember if it was divide by or multiply by 3.6
Instead I now do it as you have shown, except it all goes in the same expression.
10 km/h * 1000 m/km * 1h/3600s = 2.778 m/s
No need for the extra steps. Slap it all in the same expression and put it in the calculator (being careful to check that the units cancel as intended)
load more comments
(2 replies)
I'll be pissed if the comments are about metric units
That’s interesting. Obviously, you’d put a center dot to disambiguate millihertz from meter-hertz, but I can’t recall ever having learned a rule about that. So some combinations of units are inherently ambiguous?
Also: Hz/dpt.
I can't tell which unit is more cursed: millihertz or meter hertz. Surely, anything that could be measured in millihertz is more natural to measure as a period, or as revolutions per minute or something, right?
EDIT: Also, TIL about dpt. Thanks!
A dioptre (British spelling) or diopter (American spelling), symbol dpt, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dpt = 1 m^−1.
Something that occurs once a hour has a frequency of 277.777... μHz
You know, I always figured optometry involved like, super complicated math and shit.
Turns out it's just basic arithmetic.
Kinda like programming, in a way.
Yeah, from my experience ordering glasses, it's mostly about making sure the lenses are aligned with my retinas to focus the light in the right spots. All the numbers are just a way to formalize those measurements so that the lens maker gets it right
load more comments
(1 replies)
TIL about dpt
Tell me you don’t [Edit: need] glasses without telling me you don’t need glasses :D
I actually do have glasses, I just never bothered learning about any of the technical details behind my lenses. Optometrist measured my eyes, I chose the cheapest frame the store offered, came back a week later to pick up the glasses and that's about it.
Speed as meter per hertz is a rather odd case, like with a machine that goes in discrete steps.
In any case, I never use implied multiplication (and others) and always simply put everything where it should be.
Speed is metre hertz rather than metre per hertz. Metres per hertz would measure absement, which is a measure of how far away something is from a start point and for how long. So being twice as far away for half the time would be the same amount of absement.
Yes, sorry for the little error, my point is that m*Hz it is not generally speed but only in specific cases. Hz is not just "per time" but "something occurring x times per time", like a frequency or revolutions. You can not use it for regular speed, it has to be a periodic event. That is how it is defined:
The hertz is defined as one per second for periodic events.
This is why we have Becquerels to count decay events, which are random and not periodic, but the unit is also 1/s. And for the same reason you can not use m*Bq as speed.
I never knew that Hertz requires a periodic event. Thanks for that and the Becquerel explanation!
Thanks, I hate it
✋ 1 bit
🖖 125 millibytes
mbps, milli bits per second
Saw a video using mHz recently and it took way too long to realise the readout was correct and not a typo of MHz ..
Metre hertz? Lol
Millihertz
Wait what, jow many kilominutes per hour is one mile per stone?
African or European swallow?
Unladen or not?
Just multiply by (1000m/1km)(1h/3600s) and cancel out the units, kids
Don't ky/s over unit conversions OP. It's not that hard.
Same order of magnitude, don't bother with the trivial details.
Is it really tho? log(3.6) ≈ 0.55 so 1 km/h is really closer to 10m/s than 1m/s
It isn't even that much of a time waste you just multiply 1000/3600
But it would take me a couple of hours to figure that out.
Have you tried converting those hours to seconds?
That Hertz
I hate it when they do it !
view more: next ›