(Pressure) * (volume) = (# moles) * (gas constant) * (temperature)

The ideal gas law.

In another thread I admit I didn’t explain my position here well enough. I would only not explain this equation given sufficient context (e.g. I’ve shown all those variables in a table, and my intended audience is people familiar with basic chemistry, which I’d expect would be everyone reading the report for this particular example, since this is high school chemistry, and the topic of all reports I work on is chemical engineering.)

People can read the conclusions if they’re not familiar with chemistry, and for the detail, they’re not my intended audience anyway.

Generally I still hold the position that you should define variables as much as possible, unless it’s overly cumbersome, given your intended audience would clearly understand anyway.

In context this simple equation is obvious even if you change the symbols, as long as there is sufficient context to draw from.

No worries friend, no hard feelings and appreciate the engagement!

Yeah, agree it is a bit wishy washy in terms of gauging how much explanation to include ¯_(ツ)_/¯

I suppose (in my opinion) the mindset should be: include as much explanation as possible, without it being cumbersome.

I personally err on the side of over-explanation and have had some senior engineers give me feedback that it’s too much. Still learning for myself how much is too much.

Totally agree though, that there are many cases where people leave things out as assumed, when it’s not really reasonable to do so.

A side-thought on specificity: one of my biggest pet peeves is when people list pressure with the units of kPa, when they really mean kPag. In industry, you are rarely talking in absolute pressure (other than for pressure differences) and people then get lazy/don’t know/assume it’s fine to do something like: set point 100 kPa (when they mean 100 kPag). It isn’t fine though, because at lower pressures atmosphere counts for a pretty large percentage of the absolute value.

Understand your frustration with how I’ve communicated my position, sorry about that:

My justification for the examples I’ve given is there still needs to be other context, is based on complexity of the equation, and the intended audience of that equation.

An example of me not explaining a very simple equation would be perhaps a table of various cases:

| — | mass flow (kg/hr) | density (kg/m³) | Volumetric flow (m³/hr), V = m/ρ | | Case 1 | blah blah | blah blah | blah | | Etc. | … | … | … |

Realising now that markdown tables don’t seem to work 😅, hopefully this is still clear.

It may be a touch better to put variable symbols in the other columns, but:

1. You still have the final answer (the purpose of my report, I’m not writing a thesis here)
2. It should be plainly obvious by the units, and the fact those are the previous two variables, to someone who has the ability to understand (and is the intended audience of that little equation)

As a recent example for this, in a data sheet I recently prepared, I literally just put a * in the references column and said “*calculated from other data sheet values” for the volumetric flow rate, because the intended audience would know how to do that, and the purpose was for me to communicate how that value was determined.

Me putting in the V = m/ρ in the hypothetical example I gave above is a just a little mind jog for the reader.

Where more complicated equations are used, of course these are properly referenced, usually even with the standard or book it’s come from.

I’ll redefine my position to: Clearly define all variables, unless it’s abundantly obvious to your intended audience from context.

My intended audience of the conclusions or final values are the layman. My intended audience of everything else is someone with a very basic chemical engineering understanding.

Your last point is a strawman:

I find it a bit contradicting to the very point you made about defining variables. If anything, one might be some home-grown genius that has real business getting into details but only ever used Chinese characters as variables

Because I’m writing in English, for an English speaking audience, and there is no such thing as a home-grown genius getting into my area because it’s a legal requirement that they have an honours degree. Even still, the two assumed knowledge equations I mentioned, which I would only not reference with sufficient context, would STILL be recognisable with totally random symbols.

| mass flow (kg/hr) | density (kg/m³) | Volumetric flow (m³/hr), 容 = 质/密 | Yup, a bit odd in an English context, but with the units information (always mandatory, of course) completely understandable.

There ya go (only used it up until highschool physics, in Australia, iirc), I definitely have no business reading anything regarding voltage then 😅

Thanks for sharing

You only have to define it once in a document, book, whatever. Also, it’s not like you’d ever need to do this for handwritten notes, only for a wider audience, or if you intend for something to be read by not just you.

No one is suggesting you don’t use symbols, just that you define them, and not assume the reader uses the same symbols as you. Which, so often, they don’t. (How many different ones have you come across just in highschool and uni. I came across multiple)

I’m no physicist, but surely there is a huge range of symbols for the same thing, especially the more niche you get.

Lol fair point regarding Eng: “Engineering”.

But Nah, I think assumed knowledge of PV=nRT is fair in context, since if you don’t know what it is, you’ll only be reading the conclusion, not getting into the weeds of a calculation document.

I’m not going even going to be explaining if I have a column that’s says volumetric flow rate, with V=m/ρ. If I give mass flow rate and density (with units, of course), and use these extremely common symbols, and someone doesn’t understand, then they have no real business getting to this level of detail anyway.

I do agree that in most cases not defining your variables is bad practice, but there is some nuance, depending on the intended audience and how common a formula is, and the format of whatever it is you’re writing.

I should specify when I say physical engineering I just mean chemical, mechanical, electrical, etc. (not software), rather than physics in theory/academia.

I guess engineers are applied physics (in a particular area each), and we need to distribute our deliverables to people who aren’t necessarily experts in every discipline.

It just also makes sense to always define variables.

It’s so funny because I’ve never seen voltage defined as U, and not V haha, proving how if you’re going to have an equation, you’d better define everything, there’s so many reused letters!

Thanks for sharing

Thing is, you usually define all your variables. At least we do in engineering (of physical variety, rather than software).

Mostly because we can’t expect everyone reading the calculation to know, and that not everyone uses the same symbols.

Not explaining each variable is bad practice, other than for very simple things. (I do expect everyone and their dog reading a process eng calc to know PV=nRT, at a minimum).

Just like (in my opinion) not defining industry specific abbreviations is also bad practice.

Mathematicians don’t do this? Shame on them.

I mean, at least put it on the weekend, like other countries (or at least mine).

Allow early in-person voting centres and postal votes. Make it convenient.

Though, maybe these are only widespread in mandatory voting counties (like mine), because you’d get massive complaints if it wasn’t convenient.

Turnout is unsurprisingly, very high here.

Oh neato, then all good!

It would make sooo much more sense for the ISO to set something up, and make governments each responsible for keeping it updated, since they’re the ones doing the changing.

Require all participants to amend their law/regulations, so there’s a note to prompt whoever is in power and changes it next.

I’m sure some places would still neglect to do it… Haha

Perhaps we’ll move to UTC+10¼, and then move forward 45 minutes in the summer.

If the day number is a prime, then we’ll go back π hours.

Hope that will help!

Apparently vote.gov is a thing.

Yeah, I’d be super sus doing this via a 3rd party.

So why are they asking?

I think this pretty well describes most places in Australia, sadly. Things are, decent, in Melbourne, but I’d still never recommend it as a mode of travel unless someone lives near the bike infrastructure. Australia is still car centric, sadly.

I do still love using the infrastructure that does exist, regardless.

Yeah I couldn’t find it either. Thanks for your help!

Is this “feature” enabled mobile yet?

Or, ooor, the obvious answer of mandating the UTC in the backend.

Actually moving societies all to UTC is a really bad idea, as outlined by many others, dozens of times on Lemmy.

24 hour time though, that’d be nice. Everyone already knows how it works anyway!

As a side-note to your helpful link, I really dislike it when headlines use a comma in place of an “and”. Like, use “&” if you really must.

Print is not exactly the main way people read the news now anyway, I think they can spare the pixels!