Externet

Good day. Sound waves as speech make a dynamic microphone diaphragm vibrate. The waves hitting the ‘exposed’ side of the diaphragm make it to vibrate because has a minimal mass. If the diaphragm was massive, it would not perform well as a microphone. The back side of the diaphragm can be exposed to the same vibrations as the front, or be encapsulated shielded from being exposed to the vibrations. If the back side is not shielded, the motion of the diaphragm can have cancellation as vibrations push simultaneously in-phase to both sides yielding little or no movement. If the rear of the diaphragm is enclosed and not exposed to the front-hitting vibrations, cancellation disappears and a signal performs properly sensed. If the rear of the diaphragm is hermetic, not vented, a back side chamber ‘damping’ effect attenuates the signal somewhat. A dynamic diaphragm held unsupported in mid air yields a minimal response to vibrations as has no reference to a fixed anchoring frame. A diaphragm must be firmly held to a more massive frame of reference that does not vibrate in an appreciable magnitude. A detail mostly overseen. Please mark what is right and what is wrong above. =============================================================== If a microphone must work fitted inside a hermetic capsule to protect it from harsh environment, and still perform reasonably well, the encapsulation should be - flexible like silicone, polyethylene film ? - rigid as aluminium foil ? - have two separate chambers; one for the front of the diaphragm, another for its rear or a single ? - the microphone itself should have its back vented to inside of the capsule ? -This is about dynamic microphones; nothing is about electret condenser microphones-

Thanks. Yes, tables show water with no 'competitors' in specific heat for common available materials. A "suitable expansion vent" is not a 'closed container' Pressure builds up, vapor leaks out; same thing. How can be made it to work better being both 'closed' and 'vented' ?

Hi. Surplus energy from solar panels has been heating water during the day in a non-sealed 200 litre (55 gallon) drum and used in winter as heating source during nightime. What materials could store more energy instead of water, that along weeks diminishes level from steamy evaporation ? Oils have a lower temperature coheficient but can be heated well to >200C; perhaps yielding a greater Q = mCΔT If heating from electric elements in a oil container has lots of iron, or aluminium junk submerged, would it keep more heat ? What simple common materials as rocks, glass?, polyethilene, metal junk in oil bath (or something else) -with no phase change complications- would you choose to implement to absorb and release more heat at winter nightimes ? I see a surprising figure for pine wood at ---> http://www.engineeringtoolbox.com/sensible-heat-storage-d_1217.html

Hi. In the news, a supposedly expert opinion on that Hawaii fire said the hotter weather promotes more evaporation yielding more ready-to-burn fuel. (Makes some sense) , Is that a too simplistic point of view ? More evaporation can mean more precipitation somewhere else, does it ? Is all of this climate changing too guessy ? -The cause of the fire if was electrical sparks or not was left out of the discussion- Are coincidental events as hurricane wind, drought, season, temperature... more influencing factors than anything else in the disaster ?

Hello all. In U.S. some aircraft are registered as 'experimental' - Is there the same category for amateur built boats ? Do those need registration ? Is there any certification or approval - by who ? Anyone knows how does it work ? Is it true what I was told once that if a boat or hull is imported into U.S., must pass strict tests and hurdles to be registered and used. But if the hull is built in the U.S. even by an amateur; such restriction is not existent ?

I was thrown out of hell because when I arrived there, was asked 'Hi, how are you doing' ? and I responded 'Am fine, thanks god' !

What flaws do you perceive ? ---> https://www.youtube.com/watch?v=7cozCZAhsE0

Do not believe chinese when pricing; these read fingerprints : But none resists a

Thank you. The 'pulse' graphic at the second link appears more as 'digital' (open / closed channel) communication than an 'analog' behavior conveying varying quantitative sensations.

Whatever brain neurones do for communication among/between them; do they do it in analog or digital ? -Am not joking- When the brain 'orders' to say a word; the neurons 'orders' are received by any neurons at the lips/tongue/vocal chords or directly by their muscles ?

Thank you, studiot. +10 Never saw the 'right side' column, even at the university in neither fluid dynamics nor physics classes. Well explained and thorough.

Those many sets of threaded, gummy, slick tires for wet, dry, cold, hot track are now all very wide with more tire contact area with the pavement. Never narrow tires, which should present muuuuch better aerodynamics. Does not go well with a formula with absence of the area factor. The school taught formula F = uN leaves voids. May be just approximate; or experimental; but that is never told by the teacher. Instead, I got the babbling , stuck in retina since the sixties. ☹️ In the fifties, seems started with double tire : -Images borrowed from the web-

Hello. It was perhaps eight grade, and the friction formulas and the explanation of being independent of the contact area; asked the teacher why were then, the tires on racing cars wider. After his babbling of being 'different case' would like to know what he meant, over half a century later.🤔

If any moderator could add [botany] to the end of the title; great. I forgot.

One of these ---> https://duckduckgo.com/?t=ffab&q=httpsvivipary+tomato%3A%2F%2Fwww.google.com%2Fsearch%3Fchannel%3Dfs%26client%3Dubuntu-sn%26q%3Dvivipary%2Btomato%23ip%3D1&iax=images&ia=images Edited: Found the actual site I was reading ---> https://www.epicgardening.com/tomato-germination/

Good day. Done it many different ways year after year, bought seeds, extracted my own, dried, fermented, raw,... would like to know differences when removing the germination impairing gelatinous tissue around the seeds. Fermenting the seeds creates a mold on them that decomposes the germination impairing 'gelatin. Washing later, leaves clean seeds ready to dry them. Now, can that mold residue cause later illness of the growing plant ? Is my method of only brushing the extracted seeds in a sieve producing the same effect ? Also, some occasions seeds were planted before the drying stage. Is drying mandatory ? What differs ?

What is the process to induce seeds to sprout inside the fruit ? 🤔 Tomato:

Hello all. In a successful body weight reduction; the loss of mainly fat tissues, its mass becomes energy used by the body, or is excreted as urine, as stools, as sweat ? Where that lost mass goes / becomes ? Any byproducts too ?

Hi. Carrying a load on a vehicle takes some horsepower; pulling it shows another figure. Is there an approximate percentage that tells difference ? Like towing 50 Kg needs 40% less horsepower than carrying 50Kg ? -Images borrowed from the net-

Greetings. Too much speculation going on about what artificial intelligence A.I. will be like in the future from not clear-minded opinions. Give your grain of sand please. Will this forum survive with people or will be replaced by A.I. ? Will kids be taught QRcode at school instead of alphabet - perhaps with no teacher ? Will currency disappear ? Store clerks unemployed and people buying things talking to a display (with no need to talk) ? Yesterday went to buy a sandwich and at the register, a young 'cashier' girl behind a counter pointed me to a scanner, a credit card slot, a money slot, a receipt printer, a change vomiting machine all on the counter top oriented towards the customer and did not move a finger. What she did could be easily be replaced by a video recording. What type of activity will she perform a few years from now ? Similar at the supermarket for well over a year now, and spreading to the hardware store and more. There is no way to find a taxi, to buy a bus ticket, You are forced to pass trough the funnel of a phone application. And am not sure that is related to A.I. as has been imposed for a long time now. Will your refrigerator know what is left in it and when you voice 'prepare artichokes in oyster sauce for supper' it will place an order that will arrive by drone to an exterior door of a cooking appliance on time ? So far when I have said at a friend's house 'Hey google, make me a ham sandwich and bring a beer' that thinghy just plays music. What are real expectations, will my grandkids be glued to a 'smart' phone trying to locate some crumbs to eat ?

There is a previous thread on the subject that contributes with answers. : --->

Laziness, yes, mental laziness is the factor. And whoever says that English is evolving : NO, languages do not evolve. Languages are degenerated and contaminated by lazy ignorants. Spell check ? Wait until A.I. takes over.

Isn't speed of light / frequency = wavelenght ? and speed of light / wavelenght = frequency ? Instead of frequency / speed of light ???

Thanks. Then impulse, impact, impetus... are not to be used. Momentum it is. Now; if momentum is hv and Energy is hv ---> momentum is energy ? Where am I peeing out of the can ?

Thanks. OK. We are then not talking momentum p = mv = mass times velocity. It is then momentum p = hv = h times frequency = p = h/lambda What is h ? What is the formula E energy = hv ? Or, it is not momentum; it is impetus, or impact, or some other wording ? Is it wrong terminology ? Calling two things the same name ?