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Cake day: June 23rd, 2024

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  • ChaoticNeutralCzech@feddit.orgtoScience Memes@mander.xyzJust vibing
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    2 hours ago

    Steam engine pistons also move back and forth less than a meter at a time, and still could push trains a million kilometers in the forward direction. It’s that they’re pushing right while moving right and left when moving left. That’s like when AC current and voltage are in phase, delivering positive net power. Meanwhile, something that pulls left when moving right is consuming power.





  • ChaoticNeutralCzech@feddit.orgtoScience Memes@mander.xyzJust vibing
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    11 hours ago

    You are correct, that was a mistake.

    However, although symbols of units named after scientists (V, A, W, C, J, Ω, H, F, T, Hz, S, K, N, Pa, Bq, R, Ci) are uppercase, they are lowercase when written out (volt, amp(ère), watt, coulomb, joule, ohm, henry, farad, tesla, hertz, siemens, kelvin, newton, pascal, becquerel, roentgen, curie) to differentiate them from the surnames. Also be careful with degrees (Celsius, Fahrenheit, Rankine, Réaumur…) and grams (g, not G or gr), unrelated to the bacteria-ranking Christian Gram. And yes, the l/L debate is why the Claude Litre hoax was created. (In Unicode-capable applications I use 𝑙 BTW)


  • ChaoticNeutralCzech@feddit.orgtoScience Memes@mander.xyzJust vibing
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    11 hours ago

    The electrons don’t move very quickly either. Like, a sluggish one millimeter per second is more current density than most metal conductors can handle without melting. Thankfully, there’s lots of mobile electrons carrying charge (coulombs) so that’s a lot of current. “Electricity” only travels near the speed of light because voltage is like a force sending waves through the electric field (simplified). And it’s instantaneous current (amps = joules edit: coulombs / second) times voltage (electric field potential difference in volts = joules per coulomb) that delivers power.

    Simplifying to a single harmonic (pure 50Hz/60Hz sine voltage source and a passive, linear RLC load), you need not only multiply the voltage’s and current’s effective amplitude (that gets you apparent power in VA, voltamps) but also their power factor or cos φ (the cosine of phase beetween them) to get power in W (joules per second). If the cosine is one, it’s a purely resistive ® load (like a heater) with a phase difference of 0°. If the PF is zero, it’s a purely reactive (L/C) load (a freewheeling synchronous motor is much like that) with a current phase of ∓90° and no power is consumed overall. If the cosine is negative, power is actually being generated by the device you’re measuring (for instance, old elevators and escalators with synchronous motors are actually delivering power into mains when enough people are travelling down).




  • Probably also new enough to have a non-point-focusing Fresnel lens. Which is enough to focus sunlight into a pot and heat it up decently fast, but not to make a sharp death-beam to liquify metal. That’s the most valuable part of a projection TV nowadays, and although you could get a sizeable trapezoidal mirror and some lenses, plus dichroic glass out of LCD ones, those are not nearly as fun.

    I think that by removing the mirror, screen and case, a working one could be made into a half-decent projector but very limited in where it can be placed in the room to focus (about 1 diagonal away from the screen and dead center because of no keystone) plus you’d have to make a fire-resistant electrically safe case for the unshapely thing that blocks any light from the lamp/CRTs but isn’t too big as to block your view any more than the bare device already does.




  • Of course. You need about 1 hair per 2x2 pixels on a 1080p screen and 4x4 on a 4K screen. That totals about 10,000 hairs per icon in the simulation, which can be precomputed into animations. Third-party icons will be 2D (or 2.5D if the FG/BG layer of the icon is handled separately, doubling the animation data). Now it’s “just” a matter of drawing 10,000-20,000 lines with precomputed shading and textures from the icon’s 100x100 bitmap render.

    Also, the GPU is only used by apps while they’re in the foreground, so the launcher might be able to use all of its power. And it could cache animations for existing icons (who cares if the system uses 32 GB of storage? Buy the higher option, peasant!)