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Cake day: July 20th, 2023

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  • Are you familiar with the difference between polar (r, theta) coordinates and cartesian (x,y) coordinates? Parabolas are the solution to gravity that is uniform no matter where you sample. It assumes that gravity points in the same direction with the same magnitude no matter where you are. In this model, gravitational acceleration is always 9.81 m/s^2 in the -y direction. That is a reasonable simplification for things that are at the human scale constrained to near the earth’s surface. Deviations from air resistance will matter far more than errors stemming from that assumption anyway.

    Conic sections are the solutions to gravity that is between two objects where the force is along the line between the center of mass of both objects and the strength is inversely proportional to the square of separation. Now you need polar cpordinates and the direction of gravity changes as things move around. This works pretty well for orbits around the earth and orbits around the sun, because the earth is so much more massive than sattelites that orbit it, and the sun is so much more massive than things that orbit it. If you need really precise orbit trajectories, ellipses aren’t truly accurate either. You need to account for all the orbiting bodies in the system. The 3-body problem famously doesn’t have purely analytical solutions, and you need to resort to numerical methods to calculate trajectories.

    So both solutions come from simplified mathematical models. Despite being simplifications, their predictive power is actually very goood. However, like you are intuiting, it’s important to know when those simplifying assumptions lead to errors that start to become important. It’s hard to come up with a particular threshold for when you need to switch from one model to another, because it really depends on how much accuracy your application needs.






  • I don’t have information specific to midea, so there is some speculation, but I do have a ge unit which does outright say that the water condensate is slung across the condenser coil to boost efficiency. And yes, my ge unit got really nasty and I ended up drilling a hole in the base of the condensate pan to drain all the water.

    https://products.geappliances.com/appliance/gea-support-search-content?contentId=16758

    Heat pump efficiency is limited by the temperature delta across the compressor. The larger the temperature delta, the less efficient a heat pump is. Evaporating water off the condenser coil drops the refrigerant temperature compared to air only and gives a small boost to efficiency. I don’t think it’s a big difference, but it’s enough to be worthwhile doing if you can “get it for free.” Unfortunately, a constantly cool and wet pool is a great breeding ground for mold and pathogens that you don’t want airborne.

    As for cleaning ease, I based that off of comments (on reddit I think), recommending people push midea to pay for a technician to perform the fix because taking it apart for a thorough cleaning is a hassle. So I have no firsthand experience there and I’ll defer to your judgement.


  • I don’t have one of that type, so I haven’t contacted them. I was thinking about getting a unit like that, but then found out why they weren’t in stock anywhere.

    I think the lack of drain was intentional so that the water wiuld splash up on the condenser coil. An AC unit generates a lot more water than a refrigerator though, so I think any design with a condensate basin below the condenser coil will have mold problems. The other issue is they didn’t make the unit very serviceable, so opening it up to clean out mold sounds like a huge hassle. Draining the water away will mean the units won’t be as efficient as originally designed, but mold can be a major health hazard.




  • Fermion@feddit.nltoAsk Lemmy@lemmy.world[deleted]
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    1 month ago

    This is an x-y problem. You are asking about methods of placement when your actual concern is methods of accountability. Choosing someone else in the next election isn’t accountability, it’s a flimsy escape mechanism. Both methods of placement won’t be able to correct for a bad actor without further protections from independent/external authority.