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  1. This may connect with Uber-Dan's question . Is there a lower limit in very dilute electrolyte ? Sewage treatment by .25 Kwh removes .06g /litre Nitrogen in 1000 litres. If water has .0004 g /l. is it too dilute to efficiently drop the level to .0002 g/ l. Nitrogen? It's not home-work I'm 71 and 5 months.
  2. Strange, This is Engineering . The data is the point and words 'battle' and 'boomerang' have no effect on perpendicular fail of MPa . The title is "yield , fail in battle". This is an engineering pun on failing in a fight. Here is "battle": "NARRATIONBattles between Europeans and Aborigines occurred throughout Australia, including the Darling. Catalyst: Toorale Man murder mystery - ABC TV Science https://www.abc.net.au/catalyst/stories/4211835.htm Apr 7, 2015 - Bizarrely, the skull wounds on Toorale Man appear similar to those on gladiators in Imperial Rome. Dr Michael Westaway When you look carefully at these sort of lesions, the striations are fairly diagnostic of an edged steel weapon. So it may actually be evidence for frontier violence. This is significant because we actually haven't seen anything like this in the archaeological record in Australia before." The death of Kaakutja: a case of peri-mortem weapon trauma in an ...https://www.cambridge.org/core/product/.../core-reader Sep 15, 2016 - .....Of the weapons tested the frontal wound on Kaakutja most closely resembles that produced by an African 'Samburu' sword. These are the only calculations provided. (Soldier returns home with piece of skull-bone and asks wife to glue it back . "Did you lose it in battle, Tom?" "No, it was part of a North Korean missile strike for the heroic struggle of the Dear Leader". "That's a battle" . "No it's not". "Yes it is".) studiot, So you have boomerangs too? What's the drag resistance of sand ? What's the exit force?
  3. Strange, All the data is used to find the MPa force on a mulga-blade boomerang when cutting bone. Here's the humeral trauma: The death of Kaakutja: a case of peri-mortem weapon trauma in an ... https://www.cambridge.org/core/product/.../core-reader Sep 15, 2016 - A trauma was observed on the posterior of the right humeral head (see Figure 8a & b). A circular segment of cortical bone had been entirely removed, exposing the trabeculae, in a wound with clearly defined sharp edges, measuring 14mm in diameter. Oxford dictionary . battle fight ,..join ~ enter into combat . v. struggle. First post : "Parallel ultimate failure is 40-70MPa and by analogy the perpendicular fail is ~8 - 14MPa for hardwood." That is specific for mulga , density ~1ton cu.m , used to make boomerangs. From 4 posts back :" Reality is that a .4kg boomerang didn't cause failure in pig-skull or Synbone forensic skull. Thinner than 2mm the wood-edge buckles out to 2mm at impact. " The baseball shows the approximate forces in a similar action , blade on bone at max velocity. It is well above the ultimate fail of 2mm boomerang . Doubling the thickness will double the force-weight and halve the pressure giving the same MPa. And above 2mm the damage is random , unlike the skull image of smooth entry , floor and exit slice . The scoop-shaped cut is unlikely for hardwood compared with flexible steel.
  4. Makara festival is in January. Just found this. Skt माघ mAgha February माघ mAgha January - February maga priest of the sun. "The Shakyas were by tradition sun worshippers, who called themselves Ādicca nāma gottena ("kinsmen of the sun") and descendants of the sun. As Buddha ( a Sakya) states in the Sutta-Nipāta, "They are of the sun-lineage (adiccagotta), Sakiyans by birth." The Egyptian crocodile Sobek became Sobek Ra of the sun. Skt ra "shining" may be in *Maka ra , makara crocodile. Makara is used by both Hindus and Buddhists.
  5. First post " My inquiry is about the ultimate failure of 2mm thick wood blade at maximum human arm-speed of 40metre/sec ". Aircraft can be tested by windflow against stationary plane. The MPa force would be the same in a moving blade or stationary blade as with the bat if the same energy system ( time , distance) was used. The width of the skull trauma is around 3cm (crudely) and cortical plate excision is comparable with baseball deformation distance. The different spherical ball in fact becomes like hemi-sphere after the low-resistance spherical cap absorbs limited force. The ball may then also have about 3cm of distance like the bone chip. The bone trabeculae which was sliced is marrow and softer than cortical plates and could also resemble the baseball material. Both have skin / leather. The bone is neither plastic nor shatters but by the image is cleanly split. I believe the remaining force in the blade struck his shoulder and sliced his humeral bone , which may be compared with deformation energy of ball. A shorter time is more pressure which tends to perpendicular destruction of 2mm wooden blade.
  6. Hullo Strange "In the 1st-millennium BCE Sumerian names were not normally translated into Akkadian, but rather rendered in the original Sumerian as loan-words/scientific terms. Capricornus "Goat-Horned", from MULSUḪUR.MAŠ "The Goat-Fish", marking winter solstice. It is a mythological hybrid depicted on boundary stones from before 2000 BC as a symbol of Ea, Babylon. mulSUHUR.MASH If we omit the six names GUD.AN.NA (Taurus), SIBA.ZI.AN.NA (Orion), SHU.GI (Perseus + and northern part of Taurus?), GAM (Auriga or Capella), SHIM.MAH (south-west part of Pisces) and Anunitum (north-east part of Pisces), those remaining are exactly the Babylonian names of the later signs of the zodiac," So we have a fish constellation of mid-winter and not just any red-herring but a composite monster. Some people can say 珈琲店 and Babylonians talked to Sanskrit people in Maka when Greeks were making money.
  7. Experts don't know about this . By logic, non-experts do know. So I should get some knowledge from readers here. The Sumerian/ Babylonian father-god Ea had a goat-fish , Capricorn, suhur.mash. Akkadian. suhurmashu/i] . Sumerian Mashdagu is the first month of the year, corresponding to Capricorn. . Akkadian mashartarnu big fish. maste dried fish. Sum. Tammabukku dragon from the Land of Mash . Sanskrit मच्छ maccha fish . Hindi . makara muchch Capricorn . Makara Sankranti, Maghi, is a festival day in the Hindu calendar, in reference to deity Surya (sun). It is observed each year in January. Skt makara crocodile. ra bright , shining. The crocodile seems to be linked with the ritual and deity and may have been adapted to the capricorn fish. Mythical Animals in Indian Art - Page 45 - https://books.google.com.au/books?isbn=0391032879 K. Krishna Murthy - 1985 - In early Amaravati sculpture the makara is partly a crocodile and partly a fish with the scales and fins emphasised, It seems to derive from old India and crocodiles such as this one linked with religion: https://www.harappa.com/blog/story-tablet-harappa "In Later Hindu rituals, the water buffalo sacrifice is associated with the worship of the goddess Durga, but on this seal the sacrifice takes place in the presence of a priest or deity seated in yogic position. Above the head of the hunter is a small species of crocodile of Indus river . Similar scenes of an individual spearing a water buffalo have been found on other terracotta tablets from both Harappa and Mohenjo-daro." (Ancient Cities of the Indus Valley Civilization, pp. 11 4-5). Is the machch crocodile-fish derived from Sumerian mash fish of the god? Mugger crocodile (Crocodylus palustris) are at Sistan & Baluchistan Province, in southeastern Iran, on Makran coast. In Achaemenid times, the name Maka was used for the region and Babylon traded through it with India. Magan (also Makkan) was an ancient region which was referred to in Sumerian cuneiform texts of around 2300 BC and existed to 550 BC . The Sumerian trading partners of Magan are identified with Makran. Makara were a tribe there in 6th centAD. So its crocodile and Babylonian fish merged to become makara we know and love today. https://www.google.com.au/search?rlz=1C1CHFX_enAU797AU797&tbm=isch&sa=1&ei=BU7aXJO6BNOb9QPhm4GIAg&q=makara+borobudur&oq=makara+borobudur&gs_l=img.3..0i24.24969.28312..28617...0.0..0.287.2143.0j4j6......1....1..gws-wiz-img.......35i39j0j0i67j0i30j0i8i30.9nGz5xdvgbM#imgrc=B7lw8gkYpIfb1M: Is that how you see things?
  8. swansont, A sports record gives an approximate limit of human energy output for each muscular process. There is a constant ~40m/sec for cricket bowling , baseball pitching and ice-hockey puck hit. Would you agree that the recorded .0007sec for ball impact is reasonable for striking a skull with layer of skin ? Maybe the ball deforms half-way when stopped, then full-deformation on return velocity. A person's head likely has similar movement on impact to the half-way deformed ball. A spherical ball will not give major resistance until the bat is near final depth in contrast to the flatter bone surface. Reality is that a .4kg boomerang didn't cause failure in pig-skull or Synbone forensic skull. Thinner than 2mm the wood-edge buckles out to 2mm at impact. studiot, What "fine puncture wounds" ? Isn't a slice of forehead bone a part of your head? What sort of pub do you patronise? Do customers normally lose sections of skull or was Richard III's skull modification evidence that Yorkist politics involved pikes and swords? Can you see that I'm questioning the physics of 2mm wood excising a plate of cortical bone?
  9. studiot The skull image shows a low-angle entry which resembles axial parallel compression. Figures on bone vary widely and frontal skull compression fail ranges from 23-70 MPa. This is greater than the mulga perpendicular fail of 8-14MPa which is exceeded by the possible 63MPa stress , from the baseball analogy. Femur and frontal are both trabecular diploe bone . This author tested pigskull which didn't yield at all and he says animal leg-bone is closer to human skull ..https://www.cambridge.org/core/journals/antiquity/article/death-of-kaakutja-a-case-of-perimortem-weapon-trauma-in-an-aboriginal-man-from-northwestern-new-south-wales-australia/3E957293B27AB3CD1A30FA7F3DB2BC80 studiot , having part of one's head removed by a blade is a "battle". swansont, One source of force was the baseball pitcher who could have chucked a coke can , bag of bitcoins or 145g of fake news at max human effort to display that MPa on impact. Can you suggest another way to find whether the blade did the bone surgery?
  10. studiot, The topic can't really be described any more clearly . The following was quoted above and is not my words: "An approximate minimum cross-sectional area of the femur is ( .0003 sq m). We divide the compressive force by the cross-sectional area to find the compressive stress on the bone. Our approximate value for the ultimate strength of bone that would be required to support 30x body weight was 80 MPa, which is actually less than the measured value of 205 MPa ( compressive fail) , so the claim that the femur can support 30x body weight seems reasonable." https://openoregon.pressbooks.pub/bodyphysics/chapter/strength/ I used it as a precedent for my ideas. Bone is listed in other articles at 205MPa as a bald fact about ultimate fail . I'm claiming that the wooden blade lacks the potential to excise bone due to limits on wood thickness which limit MPa due to limit on weight and human arm-speed. The image of the skull defines what occurred to the bone. swansont, The article listed the two velocities of the ball , around 100mph /40m.sec as in the opening post about the blade. Logically, the stopping force against the ball must equal the next force to repel it. I can't imagine a closer example to the wooden blade and reasonably the times/ weights and velocities allow a general fail / no fail decision. Again , the baseball forces are only used to demonstrate my ideas and get to measured MPa and how it is handled. The resulting values seem to match reality of stress. Thanks for the comment "the physics concepts apply" as this is my purpose in posting here. Is "average force" the correct way to express the strike? Is the term "peak force" not needed in calculating ultimate fail or how does it relate to that?
  11. John, >The (average) force exerted by an object when it comes to a halt is equal to the (average) force used to accelerate it times the ratio of the distance it was accelerated to the distance over which it stops. In the 30 people situation, the forces are given without time but a is G. The baseball and wooden blade reach acceleration at point of delivery and deccelerate on contact , with probably equal time. So I used the examples as close duplicates with their force values. >It's also important to recognise that the "strength" (however you measure it) of the object which strikes a target isn't as important as people think. My inquiry is about ultimate fail of the 2mm wood as well as non-failure of the bone. The strength of each is not used to describe the other's result. studiot, The issue is in my first post. I'm struggling with what I learnt in 1964 but we're getting there. swansont, The bat F of 18,000N is divided between stopping and then repelling the ball., with about equal velocity . Then given the similarity in actions , the blade had roughly that F , delivered immediately on accelerating to stop on the bone. The image shows the deformation of the baseball and "woods used to manufacture custom pro wood bats are maple, ash, and birch. Old Hickory Bat Company" but it's not really relevant . A skull is given with cm scale attached and the blade is required to be 2mm thick. https://www.google.com.au/search?q=kaakutja+skull&rlz=1C1CHFX_enAU797AU797&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi__ZO9oJfiAhXx7nMBHdr-AacQ_AUIDigB&biw=1024&bih=625#imgrc=Y0PO_K5D7Bzu4M: image of skull
  12. Back to the drawing-board: "30 people weigh about 26,000N. An approximate minimum cross-sectional area of the femur is ( .0003 sq m). We divide the compressive force by the cross-sectional area to find the compressive stress on the bone. Our approximate value for the ultimate strength of bone that would be required to support 30x body weight was 80 MPa, which is actually less than the measured value of 205 MPa ( compressive fail) , so the claim that the femur can support 30x body weight seems reasonable." https://openoregon.pressbooks.pub/bodyphysics/chapter/strength/ https://www.acs.psu.edu/drussell/bats/impulse.htm Here we go with 9000N for ball and the same for return strike. The .145kg weight is approximately equal to the hardwood .1kg in my theory question. " If the ball contact is 5cm by 2cm= .001sq m ( see image) then the bat gets 9MPa. Perpendicular fail for bat hickory wood is around 8-12MPa. For the wooden blade on skull, contact may be 5cm by .2cm . Mass is .1 kg , same acceleration as ball. So it's .0001sq m , stress 63MPa. Perpendicular fail is ~ 8- 14MPa and skull-bone fails at around 205MPa. . Bone is OK.
  13. OK then given velocity , mass and area of contact could you demonstrate the MPa equation?
  14. 1 million pascals is rational . The gravity figure in Megapascal is not , it's diabolical and is not given as a2.  . MPa has a lot of explaining to do.
  15. Maximum velocity for baseball / cricket ball throw is ~ 100mph , ~ 40m/sec. I'm wrong to say 2mm thickness at contact , it should be .02mm sharp edge. A 5cm length of cut gives .1 sq cm. So .1kg. 402 / .1 is 1600 which is 16MPa. Maybe.