Many, many big power-smoothing capacitors inside those jumping from 0 to 120V in a microsecond, that’s why. The better-smoothed the power supply, the more capacitors and the bigger the sparks tend to be, although some really high quality ones put most of them behind inrush-current limiters to reduce the sparking, but that can also marginally reduce efficiency. High power electronics are always a bit of a tradeoff. The problem is that capacitors charge and discharge almost instantly in most cases, and when empty they act like a short circuit until they’re filled, so they can create some pretty big sparks, even though the actual energy going in is minuscule by any reasonable measurement. It’s almost like a static shock, huge spark, tiny energy.

Some motors will also spark badly when disconnected, but the reason is slightly different. They have a huge electromagnetic field which suddenly fills or collapses and that inductance in the coils can draw a lot of amps on startup and generate some pretty high voltages, more than enough to spark across the gap. Like the capacitors, they are very nearly a short circuit until they start moving.

It’s also kind of misleading. This map labels North America as 115-120V like everyone always does, when in fact it’s ALSO a 240V system, it’s just that the “common” plug and the “typical” circuit don’t use it, they only use half of a center-tapped 240V line. So that’s the “standard” they choose to use to label the whole system.

But it’s kind of unfair. It’s 240V coming into the house just like everywhere else in the world, except you also get the choice for it to be 120V. Being split-phase makes it easy to run multiple 120V circuits with a minimum of wire and still allows 240V for high-wattage appliances on their own dedicated circuits. It’s actually a very clever system and basically every house is effectively supplied with both voltages. It’s often poorly utilized, yes, with a few practical limitations and a lot of limitations due to historical conventions, but as a technical design it’s really kind of the best of both worlds, and it could be utilized a lot more effectively than it is.

If I was allowed to have an outlet with two 120V sockets, and one 240V European-style socket, there’s no technical reason I could not safely do that in a single outlet box. I could choose to plug in whatever I want at either voltage as long as it wasn’t more than 15 amps. Of course code would never allow that, because we consider the higher voltage “more dangerous” but it’s always right there, across two opposite phase 120V lines. We’re just not allowed to use it, except for large electrical appliances like air conditioners and clothes dryers. It’s frustrating.

The fuse is actually in the UK plug (the big brick-like thing with the wire on it), not the socket. But yes, it’s a thing, and most of the rest of the world considers it overkill. Also a lot of cheap junky equipment (ironically the stuff where you’d most want the fuse) omits the fuse in the plug, go figure.

No you can’t. You can lock yourself out, but a typical residential house built to code in North America has a latch handle that always turns from the inside, even when locked, and usually unlocks by doing so to prevent accidental lock-outs. And likewise if the door has a deadbolt, it must have a deadbolt with a handle on the inside. Most other kinds of locks are also easily accessible and removed by hand from the inside. The point is that they can’t require a key from the inside, because if you can’t find the key then you are locked inside and in thick smoke and fire that the key may be impossible to reach. If any egress door requires a key to unlock from the inside it is considered a serious fire hazard and will never pass a code inspection. (Of course, foolish people can still add them later but you can’t prevent stupid and it’s still a fire hazard not to mention impractical)

These types of building code and fire code rules are typically written in blood. People have died because of this.

Chargers for RC model vehicles (car, airplane, helicopter) can do most if not all of that stuff, but you will have to be comfortable with soldering connectors as there is no universal standard connector system for any of the battery types you mentioned, and even standard size 18650/21700 cells are rarely used for RC purposes. The RC hobby has mainly settled on XT60 and its smaller cousin XT30 as the closest you’ll find to a standard, but even within the hobby many batteries use other connectors. Snipping leads and soldering connectors is not an optional skill, the currents involved can be very large and will easily melt a poor connection made with poor skills or some hacky clip-on connector.

For charging, this is the sort of thing I use, no promises. RC chargers also include a balancing system to allow it to balance different cells across an entire battery pack but you will have to have individual wires junctioned in between each of those cells so it can sense their voltage and top them up as needed.

Also most RC chargers don’t bother having anything to do with lead acid (automotive style 12V or otherwise), as they are much too high amperage and heavy for any sort of RC use and they use a wildly different charging design and have much more complex health monitoring and maintenance needs. Not recommended for that, use an automotive, marine or off-grid style battery maintainer and repairer for those. The one I linked says it does handle SLA (sealed lead acid) but I wouldn’t trust it to do a good job. Compromises have likely been made. You’d be better off with a dedicated unit for those if you are going to be dealing with them.

Climate change is absolutely a now problem, it’s affecting far more people right now than acid rain ever has or ever will, it’s costing trillions and you’re already paying for it in taxes, insurance, and other ways. The fact that people don’t understand it or appreciate how significant it is doesn’t mean it’s not a “now” problem, it just means it’s not a problem that’s ever going to get fixed because people like you don’t and won’t ever consider it a “now” problem. Enjoy the challenge of struggling your way through the increasingly impossible economy, it’s not going to get better.

That’s false. You can literally not only feel heat from, but you can in fact set things on fire with, a completely monochromatic green laser with a wavelength exactly in the middle of the visible spectrum. No infrared, no ultraviolet. Lots of heat transfer. You could do it with an ultraviolet laser too if you were careful enough and could get around ultraviolet’s tendency to destroy molecular bonds completely before they even have a chance to burn chemically. It’s not just lasers either, any light source is going to deposit energy in the form of heat on anything that light touches. Any light contains a large amount of energy and some of it will get absorbed by anything it interacts with, and that’s still true whether it’s infrared, ultraviolet, somewhere in between, or all the above.

Infrared has a special relationship with heat, yes, because of the distribution of blackbody radiation, but “No” is absolutely the wrong answer here. The right answer is “Yes, but… it’s complicated”.

Tell that to Bosnia. NATO can do whatever it sees fit. It’s an organization that operates entirely by consensus. If they have consensus, they can do it.

Oh absolutely. Smart TVs are completely under the control of the technology and media companies with very little hope for freeing them, except that you can still plug a computer into them to bypass all the “smart” features and just use it as a dumb screen with a smart computer instead. But they always seem to put a few new stumbling blocks in the way of both those options every year. That loophole will eventually get closed, it won’t happen overnight, but they will keep eroding the functionalities and convenience of doing so until few if anyone wants to do that anymore.

Cars are nearly a lost cause too, except where regulations say they must use some standard like OBD2 for “emissions reasons”, although that is obviously a limited scope and manufacturers try to find any ways they can to sabotage it or otherwise avoid it. Appliances and “smart homes”, all the way down to the light bulbs and LEDs, have plenty of proprietary, locked down, unrepairable technology in them too despite reliable open standards being available. The war for total control over our digital devices is in full swing and there’s no area of our lives from large to small that isn’t a battleground. People need to keep prioritizing the freedom of their devices because once they get these technologies and features entrenched it’s going to be very hard to work around them.

I mean, they did it with phones too. Android is just Linux. That was one of the main attractions, for me at least.

At first, many people and groups supplied their own phone OSes. There was a whole thriving community ecosystem. Then they started to make it really hard, locking bootloaders and including critical pieces of hardware that didn’t or couldn’t have open source drivers (look up WinModems for a very early example of this technique, it remains really effective) or otherwise required extremely convoluted methods to access and the phone might function marginally without some of these fully functional, but at least you could still install a custom ROM on it if you were stubborn enough.

But even that wouldn’t last. Nowadays they’ve made it literally impossible to defeat the security on most phones, in the name of keeping hackers and criminals out, but really a big part of their motivation is blocking these pirate OSes that let you actually control the hardware and software in your phone, doing criminally nefarious things like stopping them from downloading ads (the horror!) and preventing them from funneling all your data and activities back to Big Brother (how rude!) and worst of all updating it with modern functionality after they’ve declared it “obsolete”. The goal going forward is to sell you things that you don’t and can’t control, so they can shut them down or make them gradually more and more useless and make you buy new ones forever. They want you to have a subscription for everything including physical objects without realizing that you’ve been forced to subscribe to their regularly-scheduled-disposable-device-replacement-plan for no actual reason.

They’re coming for computers too, or at least they’ll try. They want control of everything we interact with. For profit, mostly, but I wouldn’t rule out other motives. It’s a powerful thing when you have control of everything people see and do.

Bernoulli’s explanation and Newton’s explanation are the same explanation made from different frames of reference. They’re equal, I don’t understand why people insist that one or the other is incomplete or that they somehow both have different contributions to an airplane’s flight. They’re the same. The airplane flies because the air pushes it up turning some of the energy from its substantial forward movement through said air into enough upward acceleration to counteract gravity. That happens both due to pressure differential AND the sum of the deflection of air in exactly the same measure, they are directly linked and have to be equal. Bernoulli’s explanation is one particularly nuanced and clever way of looking at and understanding the exact mechanics of how that happens and if you plug the resulting values into Newton’s math it matches perfectly. The zero “angle of attack” for a cambered airfoil shape is actually measured this way not by measuring the angles of the physical surfaces or anything like that. The Newtonian explanation is just another way of looking at it. Either way it requires intense computations to come to exact numbers, but the numbers are the same either way. The pressure differential of the air IS the mechanical force of the air, happening as an equal and opposite direction to the deflection of the volume of air the plane is flying through, either of which is what we call lift. They’re all the same thing, happening at the same time and yes you can look at them from different perspectives but that doesn’t mean one perspective is wrong and the other is right. They’re all accurately describing the same thing. It is useful to know both, but not necessary and it does not make either of them incorrect.

This discussion always reminds me of the “airplane on a treadmill” argument where both sides read the premise differently and scream at each other that only their way of interpreting the question is right.

I got a stainless steel one on Amazon, it’s relatively thick steel, I have no idea how you’d be able to break it with only your hands and feet. I agree the plastic ones are shit.

Edit: The brand was apparently “NINEMAX”. (Not a sponsor lol)

No good reason, just historical inertia and resistance to change. People stick to what they’re familiar with, either the imperial system or to common metric units. Making a “metric ton” similar in size to an “imperial ton” arguably helped make it easier for some people to transition to metric.

Megagram is a perfectly cromulent unit, just like “cromulent” is a perfectly cromulent word, but people still don’t use it very often. That’s just how language works. People use the words they prefer, and those words become common. Maybe if you start describing things in megagrams other people will also start doing it and it will become a common part of the language. Language is organic like that, there isn’t anyone making decisions on its behalf, although some people and organizations try.