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  1. Alfreds9

    Saw characteristics influencing efficiency in sawing steel?

    Hello, I am having a headache to try understand a possibly simple real-world problem: efficiency (as in number of strokes/cumulative length needed) to saw steel, assuming a constant sawing length per stroke and a known steel sectional area. I began to think about the few assumptions I assume...
  2. Alfreds9

    Finding the acoustic point in a valley

    Thank you for your replies. You're right, I forgot to add that most sounds would probably be randomly scattered within 10m from soil level, possibly centered around a fixed point in the valley and they would be prevalently distributed in the lower parts of the valley, within half of Hmax...
  3. Alfreds9

    Finding the acoustic point in a valley

    Hello, I have a practical problem, I'd like to find the "best" spot to hear sounds in a valley (forgive me if "acoustic point" isn't an appropriate term, I just couldn't come up with anything better and scrolling an acoustics text didn't help), or at least a non-blind spot (one which instead...
  4. Alfreds9

    Water wicking up porous media and air humidity ?

    I see, thank you. I erroneously thought it was #3 since I supposed the greater surface area of porous particles could play a role into replacing water vapor content in air more efficiently than porous particles slightly closer to measuring point.
  5. Alfreds9

    Water wicking up porous media and air humidity ?

    Hello, I'd like to know which of these 3 example I sketched would have a steadier and higher air humidity at measuring point, assuming same conditions (except those illustrated as different, like porous media thickness and measuring point), water level and air turbulence within larger container...
  6. Alfreds9

    Maximum light intensity underwater during seasons?

    I see, didn't think about this, thank you very much...I always thought that zenith was zenith and it didn't vary noticeably, with temperature variations being mostly dependant on light hours and longer peak time. Where can I find peak average solar irradiation by month (meaning the average...
  7. Alfreds9

    Maximum light intensity underwater during seasons?

    Hi, I was thinking if maximum light intensity underwater during seasons changes somehow. I firstly thought about considering monthly solar irradiance (http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_INSOL_M) however I thought this would have been biased at certain latitudes due to...
  8. Alfreds9

    Pressure inside a plastic bottle filled with water and squeezed by X weight?

    I can't get my head around this (or maybe I just explained my question poorly): if one considers only the weight-bearing area as you suggest, wouldn't a smaller supporting area yield a higher pressure even if weight stays the same, something which doesn't make sense to me since I guess that...
  9. Alfreds9

    Where could I look for down-to-earth X-ray facts?

    I see, now it makes sense, thank you very much!
  10. Alfreds9

    Pressure inside a plastic bottle filled with water and squeezed by X weight?

    I (perhaps wrongly) assumed that pressure inside a bottle with a weight sitting on top should be higher than pressure inside a bottle with no weight on? Here's a sketch I did
  11. Alfreds9

    Is a motionless liquid-floating object possible?

    I've uploaded it again, hopefully this works now
  12. Alfreds9

    Pressure inside a plastic bottle filled with water and squeezed by X weight?

    I have this same question. Could the internal pressure be approximated to Force/Surface, so (mass*g)/surface area of a bottle? How inaccurate would this be? Thank you
  13. Alfreds9

    Where could I look for down-to-earth X-ray facts?

    I see thank you. I've read that while following the same rules of visible light, they reflect a lot less, how true is this? Thank you for the links
  14. Alfreds9

    Is a motionless liquid-floating object possible?

    You're right, of course here it is. [Questionable link deleted by moderator. See the image in post 9 instead] Basically just a small-ish floating stand. Thank you
  15. Alfreds9

    Where could I look for down-to-earth X-ray facts?

    Hello, I'd like to know which book or papers I'd read to understand, possibly without too rigorous mathematics knowledge, how do photons like X-rays or gamma ones reflect off surfaces and attenuate through solids or generally speaking, facts about how do they interact with the real world. So...
  16. Alfreds9

    Is a motionless liquid-floating object possible?

    Hi Simon, thanks for your reply. Unfortunately it's not a real homework but just a project of mine, so I don't have hints to look upon. Ok I'll look at these.
  17. Alfreds9

    Is a motionless liquid-floating object possible?

    1. Homework Statement Do you think it's possible for an object to be relatively motionless if floating on rippled water surface? Could this be achieved by have it float inside one (or several nested) water/oil-containing containers? 2. Homework Equations ES = - n2(k-m)2 Lucassen's...
  18. Alfreds9

    B Visual proof of being at altitude?

    Sorry I didn't get what you wanted to say, maybe I misunderstood? I'm not trying to proof that I'm not on plane but rather that I'm at 10,000 feet. Mostly myself, but anything that could come handy as additional future proof of my hikes.
  19. Alfreds9

    B Visual proof of being at altitude?

    No problem, it will be outdoors, on solid rock :) I'll try to explain it clearer: I'd like to take a photo or video that can somehow testify (within its obvious limits and tampering possibilities) that I took that at altitude instead of sealevel. Thank you :)
  20. Alfreds9

    B Visual proof of being at altitude?

    That's simple enough and is pretty solid as proof, didn't think about this :) Pretty neat, thanks. Thank you By proof I mean something which shows I'm altitude (not necessarily at X altitude, even just at X > 10000 height) and is not only a selfie photo of me with a canyon below :) Really...
  21. Alfreds9

    B Visual proof of being at altitude?

    Hi, this may seem like an odd questions to most of you but I'd still like to ask what could be some visual proofs of being at high altitude, say 10,000 feet above sea level. While any said proof is not extremely rigorous or untamperable and probably little more than a showy capture to add to...
  22. Alfreds9

    Calculating air pressure from altitude, RH and temperature?

    I see thank you, maybe I'm mistaken with air density lowered by humidity. However, why is there no measured T rather than resorting to sealevel T and lapse rate?
  23. Alfreds9

    Calculating air pressure from altitude, RH and temperature?

    Homework Statement [/B] This is a practical problem, no homework question. I'd like to determine pressure (and O2 partial pressure) at altitude, yet following a more realistic real-world calc including measured data like relative humidity (RH) and temperature at that altitude, yet all I can...
  24. Alfreds9

    Is it possible to estimate a light source wattage remotely?

    I'd like to know if it's possible to roughly estimate a light source wattage remotely, knowing the distance and perhaps estimating that at such a distance it's still above the minimum human recognizable threshold at night (in a light polluted area). Maybe using a DSLR camera could help by...
  25. Alfreds9

    Water evaporation, temperature, wind and heat capacity?

    The results are that I unfortunately still don't see where does surface water temperature (due to high irradiation VS low irradiation) comes into play in either Penman's or Shuttleworth's formula. I am quite sure that, considering everything else equal, water at say 23°C evaporates more readily...
  26. Alfreds9

    Water evaporation, temperature, wind and heat capacity?

    Hi, I'd like to know how I'd put together, either elegantly or at least in physical terms, that surely water evaporation in a large pool of V volume and S surface is influenced by wind (increased by it as opposed to having side barriers), temperature (increased by direct sunlight as opposed to...
  27. Alfreds9

    Capillary action speed formula?

    Thank you so much, it was exactly what I was looking for! :)
  28. Alfreds9

    Capillary action speed formula?

    Hi, I was looking for a formula to describe capillary action speed in a medium. On wikipedia (https://en.wikipedia.org/wiki/Capillary_action) I came across a formula which describes the cumulative volume of a liquid drawn by capillary action after time t where V is cumulative volume, A is...
  29. Alfreds9

    Maximum useful matrix size for radiation counting?

    Hi, I'd like to know if there is a maximum matrix size after which radiation counting (using a scintillator/photomultiplier) on a flat paper sample doesn't improve or is not significant. Specifically this would refer to radiochromatograms, or chromatography strips of radioactive samples. If...
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