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  1. Anachronist

    I Equalizing airflow through multi-hole orifices

    That's what I thought. However, the effect I observe is the opposite of what would be expected (higher rotation when exhausting through the 8 hole side instead of the 6 hole side) so maybe the runner blade area is having a greater effect, which may be mitigated only slightly by the greater...
  2. Anachronist

    I Equalizing airflow through multi-hole orifices

    I know the Bernoulli equation for calculating the air velocity through a pressurized hole, but I am wondering if one hole of a given area behaves the same as multiple holes with the same total area. The Bernoulli equation doesn't make a distinction. Background: As a personal 3D design and...
  3. Anachronist

    Wordle Lovers - Play the NYT Daily Game

    Either that, or you're likely to get it in two tries 2% of the time. In the Wordle app histogram, my performance is 8 correct answers in two tries out of 244 games played. So I'm hitting 3.3%, slightly above that average of 2%.
  4. Anachronist

    Wordle Lovers - Play the NYT Daily Game

    More useful than just a result given by the NYT, is the distribution of results. The Wordle mobile app does this, although it has a lot of annoying ads. My distribution has a mode at 4 tries. I suspect it's a Poisson distribution just by the shape. Out of 244 games, I got the word correct 0...
  5. Anachronist

    If Up to You, Would You Live in Natural Disaster Prone Area?

    I did not, as should be abundantly clear if you read my post without selectively quoting it. The earthquakes were in a different paragraph. The climate change related disasters were in a separate paragraph. My point still stands, that climate change has increased the geographic area in which...
  6. Anachronist

    If Up to You, Would You Live in Natural Disaster Prone Area?

    You forgot earthquakes in California, the potential volcanos waking up in Washington and Oregon, and the whole "tornado alley" (not just Oklahoma). Practically the whole United States has disasters nowadays due to climate change. Extreme heat in the midwest. Wildfires in the west. Brutal...
  7. Anachronist

    B Occam's razor in science: all-time practice or modern fashion?

    I don't know where you went to college, but where I went to college (40 years ago) Occam's Razor was indeed a thing. I recall the topic coming up in the context of quantum mechanics, and at the time I remember thinking that some things about quantum mechanics could be considered an exception...
  8. Anachronist

    Where to find detailed control panel pictures of nuclear plants?

    There's a lot to choose from: Those seem a bit complex for a video game, particularly if the control room must include a staff of people to run it. One common element I see in a lot of...
  9. Anachronist

    I Humming top acoustics

    Oh, my. I sure was wrong. The page explains that these tops don't use whistles at all. This isn't a Helmholtz resonator as I initially thought. It's a harmonica! The ports on the side aren't whistles, they are exhaust ports. Air is ejected...
  10. Anachronist

    I Humming top acoustics

    I did google searches for "humming top innards", "how humming tops work" and many other things, and I did not come across that site. In fact, the author of that page also had my experience. He says: "... I attempted to find the answer on the Internet. For once Google let me down. No matter what...
  11. Anachronist

    I Humming top acoustics

    I remember having a humming top toy when I was a small boy, and I vaguely remember it made a sound when spun. Here's a 30-second example: ...and more examples are available on YouTube. It's interesting to me that the sound doesn't start right away after the driving force is removed. It builds...
  12. Anachronist

    Today I learned

    That explains why, whenever I started a relationship with a new girlfriend in my youth, I would come down with a cold 100% of the time after the first kiss. People are big bags of germs, everyone has their own unique collection of them, and in any new relationship I had to acclimate to the...
  13. Anachronist

    Why is my homemade DC motor not working?

    I was once in a class where we made a DC motor like this. It didn't work because one of the coils was wound in the wrong direction. Both armatures were therefore working against each other.
  14. Anachronist

    Construction How to cut a board so that it can be bent spherically?

    It depends on how close to a sphere you want to get. An icosahedron can be unfolded into a flat sheet. If you include some extra triangles in the spaces available, you can include overlapping facets that can be glued together. An icosahedron doesn't have an equator, but there are plenty of...
  15. Anachronist

    B Why does light diffract into only seven colours?

    As others have noted, "indigo" generally isn't used nowadays. Instead of the 7-color spectrum ROYGBIV, I'd remove "I" (indigo) and add "C" (cyan) for ROYGCBV. Still seven. It also makes more sense to break down the color categories into six groups, corresponding to each color receptor type in...
  16. Anachronist

    Construction How to cut a board so that it can be bent spherically?

    I cannot tell if you want to tile a concave or convex spherical surface. Either way, you won't be able to do this with square tiles, if that's what you intend. You can lay square tiles into a concave sphere but you'll end up with odd-shaped gaps. An easy sphere approximation would be an...
  17. Anachronist

    Relativity Good Beginner's General Relativity Books?

    I agree with others that you should get an understanding of Special Relativity first, and then move on to General Relativity. For Special Relativity, try this "for dummies" article: I don't...
  18. Anachronist

    B Beam of air: Extending the range of a fan

    OK, a blower fan then. I'd probably use this one. I know such a fan can easily blow air across the width of the printer. The question is, how does the air jet spread? Ideally, the amount of air impinging on the motor housing should be about the same 5 cm away or 30 cm away. I can design a...
  19. Anachronist

    B Beam of air: Extending the range of a fan

    I'm having trouble imagining how that would work. This is what the extruder ("print head") looks like. The extruder motor that I want to cool is the cubical-looking object with the words on it. That motor is what forces the plastic filament (not shown) into the hot end at the bottom and out the...
  20. Anachronist

    B Beam of air: Extending the range of a fan

    That makes sense. I am thinking now that a centrifugal fan with a nozzle that sucks in air to control the shear around the central flow might help, in the way that the high-pressure nozzles linked above create a protective sheath to keep the air jet collimated. In all my years I had never heard...
  21. Anachronist

    B Beam of air: Extending the range of a fan

    After some searching, I found that there are compressed-air nozzles designed to create a laminar stream of air to exert a focused blowing force over an extended distance (example 1, example 2). They apparently surround a high-speed central jet of air with slower-moving protective sheath of air...
  22. Anachronist

    B Beam of air: Extending the range of a fan

    Ah, I remember those pulse toys! In my experience they were used mostly to annoy other people! It looks like it's using a nozzle with an exponentially decreasing radius, over a large diaphragm. Sorry, I thought that might have been clear when I said this is for a fan. It would be continuous. My...
  23. Anachronist

    B Beam of air: Extending the range of a fan

    If one Googles for "laminar flow nozzle", one finds many interesting tutorials on creating a nozzle for a laminar water jet; a stream of water that remains coherent over a long distance without breaking up. These typically consist of a large-diameter tube with regions inside (like sponges and...
  24. Anachronist

    B Why does light diffract into only seven colours?

    No, actually there is cyan in all rainbows, as well as white light split by a prism. But there is no magenta.
  25. Anachronist

    News Weird News Compilation

    The thing is, she's still lovely without her hair. There are a few women who can get away with that.
  26. Anachronist

    What Sci-Fi got Wrong

    Yes, I am 100% sure. The episode was The Royale, and the gaffe is documented in the Wikipedia article about that episode, in which Geordi LaForge (not Data) says the temperature is -291°C.
  27. Anachronist

    What Sci-Fi got Wrong

    That reminds me of the original Battlestar Galactica series, in which nobody thought twice about having microphones connected via a cable to a console. Then in the latest series, this was "explained" as being more secure than using wireless devices to communicate. That's true if nothing is...
  28. Anachronist

    What Sci-Fi got Wrong

    Science fiction books, at least the ones I've read, tend to get known science right, and whatever hypothetical science is needed for the story, well, it doesn't matter, that's up to the author. Science fiction television and most movies, however, are replete with errors. A specific example...
  29. Anachronist

    Engineering Still Struggling finding a data science job

    I know this is an old thread. This question was directed to me and I missed seeing it. In my experience as a hiring manager, if you're trying for a job in which your skills may not be a match, I would want to know how you approach and solve problems, but even more, I would want to know if you...
  30. Anachronist

    News Weird News Compilation

    A Research Vessel Found SpongeBob Look-Alikes A Mile Under The Ocean's Surface Not too weird, but at least it's science-related.
  31. Anachronist

    Fundamental frequency of a rectangular-cavity whistle

    Update: It occurs to me that maybe I can approximate this by using the formula for the resonant frequency of a tube open at one end: $$ f=\frac{nv}{4(L+0.4d)}$$ where ##n=1## is the first resonance, ##v## is the speed of sound, ##L## is the cavity length, and ##d## is the effective diameter. I...
  32. Anachronist

    Fundamental frequency of a rectangular-cavity whistle

    I designed a parametric CAD model of a whistle that can be 3D printed. Basically I designed the internal airspaces, put a skin around it, and printed it. Combine two of these in the same enclosing body, with slightly different frequencies, and you get a warbling sound similar to a pea whistle...
  33. Anachronist

    How do I calculate the tension on top of a pole?

    Zero. If the block is perfectly balanced, there is no tension in this situation, only compression.
  34. Anachronist

    Engineering Creating a decoder (Graycode to Binary) using 4 nands

    I'm hazarding a guess here, but I think that if you write out the logical expressions using 8 not-ands, you may be able to combine common terms to reduce it to 4 not-ands.
  35. Anachronist

    Job Skills Should a resume include a "summary" section?

    I admit that would get my attention. And DON'T put the heading "Objective" or "Professional Summary" at the top. Just put your contact information and below that, introduce yourself. I don't care if it's an objective or a professional summary, I want to know who you are. Your first sentences in...
  36. Anachronist

    Engineering Measuring the damping frequency from an oscilloscope reading

    The frequency of the green squiggle is the damped frequency of oscillation. You'd have to use your equation to solve for the undamped frequency.
  37. Anachronist

    How does the surface of a refracting prism become reflective?

    Maybe this Wikipedia article will help:
  38. Anachronist

    I Why is the position of a massive particle not blurred?

    Classical physics breaks down at the subatomic level. Macroscopic objects with a definite momentum still have a blurred position but the blurring is so infinitesimal that classical physics is good enough. Heisenberg's uncertainty principle, expressed as the product of position and momentum...
  39. Anachronist

    Any plausible non-rocket based method to reach orbit?

    The title of this thread uses the word "plausible" but the content discusses implausible things. With that in mind, I think a gravity repulsor would be best. A geostationary elevator would work just fine, as long as it's center of mass is in the geostationary location. It could extend a cable...
  40. Anachronist

    2019 Goes Differently.... How?

    Sounds like dispassionate killing in cold blood would increase, possibly as a source of joy, because anger and sadness don't exist. The killings would be efficient and quick to eliminate the disgust.
  41. Anachronist

    Coriolis force caused by tangential velocity

    It isn't a force, it's an effect that has the appearance of a force to an observer in the rotating reference frame. To an observer outside that reference frame, no forces are acting on the object other than the usual (centripetal, gravity). If you sit on a rotating disk and roll a frictionless...
  42. Anachronist

    Physics Is a physics career's main focus Discovery and not Invention?

    I didn't mean to imply there was a clear boundary. In my first post in this thread I did write that there's a large overlap. There's even a job title "Engineering Scientist" to blur things even further!
  43. Anachronist

    Physics Is a physics career's main focus Discovery and not Invention?

    Interesting. My view of the scientist's duties to "observe and explain" and the engineer's duty to "create" are quite similar to what Teller described: the scientist's' duty is to "understand and explain" and the engineer's duty is to "apply". We're basically on the same page.
  44. Anachronist

    Why do I keep finding more new rocks in my garden year after year?

    If you ever visit Croatia, particularly the island of Brač, you'll be struck by the sheer amount of stone the locals have to deal with. To get any sort of useful land, you pick up a rock and move it to the border of your property. Then repeat until your land has enough dirt with few enough rocks...
  45. Anachronist

    Physics Is a physics career's main focus Discovery and not Invention?

    Well, there are some quotations on this subject here: although I am not sure if any of them are what you had in mind. In my view, scientists observe and explain, while engineers create. There's a large overlap...
  46. Anachronist

    B What are the general calculus concepts used in classical physics?

    Differential equations and integrals. Ask a generic question and you'll get a generic answer.
  47. Anachronist

    Plumbing Repurposing House Plumbing

    What a great prank! It's a good thing they didn't test the toilets. That would have been a waste of good beer.
  48. Anachronist

    Net Displacement: Calculate x,y & r,θ

    Strictly speaking, there isn't sufficient information to answer the question. Your net displacement depends on your starting coordinate, because we live on a globe. Think about it: If you started that trip 1 mile north of the south pole, traveling 6 miles east would take you in a circle around...