• Dragon Rider (drag)@lemmy.nz
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    3 days ago

    Fellas, there’s no point arguing with the flight attendants about wireless signal safety. Just smile and lie that you’ve switched it to airplane mode.

    • LwL@lemmy.world
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      3 days ago

      Yea, they just have to enforce it, not make sensible rules. Just let them do their jobs in peace and go petition the relevant aviation authorities if it bothers you that much.

    • lime!
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      3 days ago

      it’s not for safety anyway, it’s to prevent the cell towers on the ground overloading when 200 phones connect and then disconnect in a second.

  • cranakis@reddthat.com
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    3 days ago

    I can’t find the revolving door! What level is it on again? What side of the building? Damnit, I feel so inadequate.

  • renzev@lemmy.world
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    3 days ago

    Until all the lights flicker in the lobby

    OK but is this actually a thing that happens? Can the door motor feed back into the grid, or are there safeguards against that?

    • BearGun@ttrpg.network
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      3 days ago

      As a prospective electrical engineer, i sure hope there’s a safeguard against that, since i believe it would be quite simple and cheap to include. If you spin it fast enough you might overload and fry it though, even if it is there.

      • Buddahriffic@lemmy.world
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        2 days ago

        Would it be possible to put the energy generated back into the motor to make it easier to spin it faster? Maybe use some capacitors to have it switch between generator and motor mode on a repeating cycle?

        • BearGun@ttrpg.network
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          2 days ago

          It’s definitely possible, but I’m having a hard time trying to justify it. The amount of power a motor like this would draw i very low, so a few percentage points here or there doesn’t matter. The complexity of the circuit can quickly become fairly complex with something like this and i doubt the extra manufacturing costs would be worth it. Especially not for the seller, since they could easily (and probably do) just write in the warranty or whatever to not spin it excessively.

          • Buddahriffic@lemmy.world
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            2 days ago

            Yeah I was just curious because it’s a difficult thing to wrap my mind around on the physics side of things. Like it is capable of generating energy and that energy could be used to spin the motor, but the two parts are opposites. It’s like using the energy from a flywheel to spin that same flywheel.

            • cam_i_am@lemmy.world
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              22 hours ago

              In general it is often true that a motor and a generator are two sides of the same coin.

              If you put a current through a wire you can make a magnet move which can be used to spin a motor. And symmetrically, if you spin a wire and make its magnet move near a wire you can induce a current in the wire.

              Depends on the exact wiring and stuff but yeah sometimes you can damage a motorised device by manually spinning the thing without turning it on.

  • Hadriscus@lemm.ee
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    2 days ago

    Can someone explain this to me ? Imagine I’m neither a native english speaker nor a revolving door engineer