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Joined 8 months ago
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Cake day: June 10th, 2024

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  • What I find annoying is when some talking head says all code should be a certain way,

    It’s quite useful to have “all code be a certain way” within a language ecosystem. E.g. Haskell requiring all pure functions be actually pure is amazing because you know that any function from any library doesn’t perform some stupid side effect when you call it, and just processes its inputs into an output. Of course, functional programming tools can be useful even outside purely functional languages, but having those important properties be ecosystem-wide makes you feel much more comfortable, and produces much better, safer and more reliable code in the end.


  • But instead, the device turns on (nearly) instantly. Because the wire isn’t actually what causes the device to turn on

    That’s not exactly true. In this case, the energy transmission would go like this: (change of electric field in the little bit of wire next to the power source) -> (change of magnetic field in the air between the wires) -> (change of electric field in the wire next to the load). This limits the amount of energy transmitted significantly and incurs a lot of losses, meaning if you had something like a lamp plugged in it would start glowing extremely dimly at first (think about how some cheap LED lights keep glowing even with the switch off - it’s similar, albeit it happens due to inter-wire capacitance and not induction). It would then slowly ramp up to full power over a course of a year.

    Here’s a video from the same person about it: https://www.youtube.com/watch?v=2Vrhk5OjBP8 (although I haven’t watched this yet)

    Edit: after watching the video, I think I was actually wrong in a couple of my assumptions. First of all, it looks like the reason for the initial energy transmission is wire capacitance and not induction, so (electric field in wire) -> (electric field in air) -> (electric field in wire, in the “opposite direction”, but because the wire goes back and forth it’s the same current direction). This means that my LED example is even more potent. And the second one is that because it’s capacitance and not induction, this means that there’s no slow ramp-up, it just makes the light glow very dimly all the way until the electric field makes it through the wire, and then it ramps up very quickly.




  • It’s actually 0.06 microseconds (0.00000006 seconds) per day, or ~22 μs (0.000021915 s) per year.

    Also, technically, anything moving up or down in Earth’s gravitational field while physically connected to it is having an effect, however it’s usually to small to be reasonably measurable.

    (I wonder what would happen if the rotation speed was changed by 0.06 seconds per day - that feels like a lot, adding up to 22 seconds per year, but would anyone except timekeeping nerds actually notice? I don’t even know how to begin figuring something like that out.)


  • Therefore a graduated cylinder that is 10m tall needs to resist the same amount of force as a dam 10m tall regardless of how much water is behind the dam. Even a thin sliver of water 1mm thick and 5m tall has the same force as a 5m lake behind the dam.

    Technically only the pressures are equal, and the actual force will be linearly dependent on the area of the dam (or the surface area of the cylinder). That’s why you can make a tall water tank with relatively thin walls, but an actual dam will have to be quite thicc to handle the tensile/compressive stress (depending on the shape of the dam).