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Cake day: March 17th, 2024

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  • To be honest most of the basic physics behind rocketry actually isn’t too difficult. The matter of engineering it into reality definitely is very difficult, finding fuels that burn hard enough and figuring out how to contain them while they burn and the like. The nature of going so far and so fast also means that tiny errors add up to very big problems.

    All rockets function on the fact that if you push something in one direction, you also go in the opposite direction by a proportionate amount. Lighting fuel on fire while it’s in a tube that only has one way out just happens to be a great way to push the burning fuel really, really hard and therefore get a really hard push back. The forces involved always have to cancel out the total momentum of everything involved; you chuck X kilograms of burning fuel out of the back at Y metres per second, you accelerate forward by however much you need to to make your momentum match that in the opposite direction. This is Newton’s third law of motion, the “for each action there is an equal and opposite reaction” one

    Nozzles and the like can adjust which direction the way out is pointing. If the way out points left a bit, the momentum of the fuel is also going left a bit, so the reaction momentum you get goes a bit to the right, and now you have steering

    I think the biggest conceptual block people usually have about orbits is that they’re not about going up fast, they’re about going around the Earth fast. If you point your rocket straight up and just keep going straight up, you won’t go into orbit around the Earth. Either you’ll crash straight back down when you run out of fuel, or you have a rocket with enough power and fuel to reach Earth’s escape velocity, in which case you’ll just continue travelling away from Earth forever until you find something else’s gravity. You know the kind of arc that a ball has when you throw it? Imagine that you’re superhumanly strong and can throw a ball literally however hard you want. You could throw it beyond the horizon without breaking a sweat. Once you’re throwing it that hard, the curvature of the Earth starts to become relevant, right? The ground is effectively dropping away underneath the ball as it travels forward, letting it fly farther before it hits the ground. Eventually if you throw hard enough, the curvature of the Earth turns away from the ball at the same rate as the ball is falling. The ball is now in orbit. The ISS (and anything else that wants to orbit at the same altitude) goes around the Earth so fast that it does 15 entire laps around the planet every day

    Unfortunately for our rockets, the Earth’s atmosphere is very bad to actually move through that fast, so they go up first to get out of the thickest part of the atmosphere and then gradually turn sideways to achieve orbit

    Once you start getting into things like how to get from Earth to other planets you’ve got to worry about some other stuff, but this comment is probably getting long enough by now and not many of our rockets do that yet

    I totally get what you mean about planes not looking like they should work. The size of them and the fact that we’ve got basically nothing to reference them against for scale and motion when they’re in the air is really confusing



  • It’s about as close to a random person as you can get while still being recorded. They were royalty, but the two real ones get literally a sentence each at max

    • Eithne ingen Bresail Bregh married the king of Tara and is described as “having deserved reward from God for her good works, and for her intense penance for her sins” in one source and “deserved to obtain the heavenly kingdom, having done penance” in the other
    • Eithne ingen Cinadhon was the daughter of a Pictish king and is literally only recorded as having died
    • The legendary Eithne is the daughter of a king of Scotland (mostly Pictish at the time) and crossed the sea to Ireland, where she gave birth to the hero Túathal Techtmar. This is the entirety of her role in the story; a couple of paragraphs in a collection that, in the translation I’m looking at, has 600 pages just for part five

  • Not sure if I can call this knowledge since I don’t know if it’s true, but I think I identified a couple of women from the 8th century CE who are mentioned in some Irish annals as actually being the same person. As far as I know there’s next to no discussion of these women on the internet and there are basically no historical records of them, at least. So I guess if I’m right it’s very obscure?

    The women in question are Eithne ingen Bresail Bregh and Eithne ingen Cinadhon (and possibly also the legendary Eithne mother of Tuathal Techtmar)




  • We’ll have lots of English speakers here given the language the question was asked in, so I’ll do Gàidhlig (Scottish Gaelic) instead: dìochuimhneachadh, at 17 letters. It means “forgetting”, and it is pronounced /ˈd̥ʲĩə̃xənəxəɣ/. No, I can’t say it smoothly.

    Gàidhlig isn’t one of those languages that can compound words like Finnish or German, this one is just a consequence of a few different things. Firstly, the language’s spelling rules result in a lot of letters that do impart information but aren’t directly pronounced. Consonants have two forms depending on which of two sets of vowels they are next to, so any consonant or consonant cluster must always have vowels from the same set on either side. For example, the “i” in the “imhne” bit in the middle is basically only there to match the “e” at the end, since u and e aren’t in the same set of vowels and we need to know which version of the consonants between them to use. Every h is a modifier on the consonant preceding it as well. Second, the root of it is “un-remember”, so it’s already a shorter word with a prefix. Third, we’re using the verbal noun version, so it’s “the act of forgetting” rather than present-tense as in “currently forgetting something”

    There are probably longer words in the language, but I don’t know it very well yet and this was the longest one I could find on a word list. I think there’s actually a version of dìochuimhnich that includes a suffix marking it as being a conditional first person plural doing the forgetting, so “we would forget”, but I don’t understand how that part of the language works. If I was to say that at the moment, I would use two words to do it, so I don’t feel like I can give it as an answer here




  • That’s kind of them! But you will probably need to replace that car in the future

    I’m not trying to tell you that you absolutely must learn manual. Whether or not it makes sense to do so basically just depends on your personal circumstances. I learned manual, but I live in a country in which automatic gearboxes were pretty rare until quite recently and I enjoy driving (much as I support replacing most driving with public transport). I just wanted to bring up the second hand market as something to consider


  • Skua@kbin.earthtoAsklemmy@lemmy.ml*Permanently Deleted*
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    3 months ago

    One other thing to add that I don’t see mentioned yet: if you can drive a manual, you have more options when buying second-hand cars. How many more options will vary depending on where you are, but if cost is a significant concern then it might let you get a much better deal



  • I find the concept interesting, but I recognise that my own motivation and knowledge of linguistics are significantly short of where they would need to be to make a conlang myself. I have played around with around with VulgarLang a fair bit, which allows me to fake a conlang to my design juuuust enough to do the job for the purposes of tabletop RPGs and such.

    Does Silbo Gomero qualify as a conlang? It was made by adapting a way to speak the Guanche language through whistling into Spanish, but I’m not clear enough on the origins of it to know how “constructed” it is. I suppose it can also be considered to just be a version of Spanish. If it does count, it’s my favourite