I need sleep

  • addie@feddit.uk
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    2 days ago

    A kilogram of bread is about 2000 calories, about 9 kJ. Your body “burns” food too - probably more efficiently than you could make a steam engine for the same, but it’s about that much.

    Energy from gravity is equal to mass * gravity acceleration * height. 1 kg of bread in a 9.81 m/s/s field has the same gravitational potential at “about a kilometer”.

    If you’re throwing magic stake baguettes off the top of the Burj Khalifa, the energy would be about equal.

    • davidgro@lemmy.world
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      1 day ago

      Friction (as in the atmosphere) would matter a lot in this case. Bread is low density and would have a rather low terminal velocity. Basically doesn’t matter how high you drop it from.

      (until high enough that you are letting the burn part happen on the way down, but then it’s difficult to capture that energy)

      • addie@feddit.uk
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        23 hours ago

        True. I’d mentally envisioned it as a whole series of “bread powered water wheels” down the side of the building, with a furnace at the bottom. Nothing actually going fast enough for friction to matter. A machine that only tried to convert all the kinetic energy at the bottom would be wasteful, as you say.

        Plainly, we’re going to have to put some engineering design time into the concept of this.

        • davidgro@lemmy.world
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          10 hours ago

          Oh yeah, that does make a lot more sense that way then I was thinking of. (Like having it fall a long way then hit a lever or something)