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OldChemE last won the day on October 14 2019

OldChemE had the most liked content!

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About OldChemE

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  • Birthday 07/13/1946

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  • Location
    High desert Nevada USA
  • Interests
    All things science, golf, tutoring grandchildren, developing cartridge designs for old rifles (experimenting with various types of gun powder, various bullet designs, various ballistic results, target shooting), working with my hands (wood/metal).
  • College Major/Degree
    BsChe, MSNuclear
  • Favorite Area of Science
    Physical Sciences
  • Biography
    38 years engineering, 10 years teaching (Math & Science) I'm not much of a debate person. I have confidence in myself (worts and all) so I tend to state my position on a topic and move on. Peer approval isn't high on my needs list.
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  1. Yes-- frustrating-- but not without purpose. It facilitates part numbering. For example, 787ST-24 is a model 787 hose, super tough cover, 24/16 ID. Virtually every industry over the years has faced the issue of creating meaningful part numbers primarily intended to be intelligible to professionals in their industry. This is just one example.
  2. By now I presume you will have already found your answer. But-- if you are still struggling with dimensional analysis maybe a teacher's perspective will help. 1.. You have two pieces of information: liters used and km traveled, but the question asks for efficiency in km/L So, step 1: you need numbers arranged in a ratio that matches the desired answer. It wants km/L (a ratio), so the ratio has to match: 100100100 km/88 L Here, we made a ratio using the actual numbers making it so that the km's are on top and the L's on the bottom so that it matches the units in the required answer. Step 2, do the math (100100100 divided by 88) Step 3: you now have a number that has the units of km/L this is your answer. Think about this: We look at the dimensions that the answer is supposed to have, and form our ratio so that the arrangement of the dimensions we have matches the arrangement of the required answer (that is, km on top of the fraction and liters on the bottom). Then, we put in the numbers in the same arrangement and do the math. This is what Dimensional Analysis is all about: Using the dimensions of the answer we want to decide where to put the numbers in the math.
  3. If you want a 'real' answer I'm not sure it can be done very easily. It will depend on the friction losses in the tube, which depends on configuration, length, surface roughness and even the shape of the exit in the end of the tube. Sorry to not be very helpful.
  4. And the remarkable thing in my view is that the sequence in the periodic table correlates so well to both the number of neutrons and protons in the nucleus and the sequence of available valence electrons, and to the actual energy levels of electrons (s, p, d, f, etc), even though this information was unknown at the time. The real value of the Periodic Table is that it groups the elements in ways that reflect their chemical behaviors--a very valuable 'shorthand' way of understanding the elements. Perhaps there are a few places in the table that minor 'tweaks' might be of value, but I don't know off hand where those might be. For a while after retiring from Chemical Engineering I taught High School chemistry. The Periodic Table proved to be an excellent way to give students the "Big Picture" of Chemistry.
  5. This is difficult to interpret-- but I notice the heading says 'Expands the least expensive node first.' So-- my interpretation is that the red dashed lines are intended only to indicate the order in which the pathways are tested-- not the actual path used. The dashed line from A indicates that the first path examined is from A to C, because the cost from A to C is less than from A to B. The red line from C to B is only to indicate that the next pathway examined is the one that leads to B (from A). The next path examined is the one that leads to D from C, the next is the one that leads form B to D. The next is from D back to B (pathway ACDB - which fails) and finally the next pathway examined is ACDE, a success. In other words, I'm postulating that the red dashed lines show the order in which the algorithm tests destinations, not the path taken to test them. Summarizing, the system keeps testing paths starting with the least values until it finds the solution. The paths tested, in order, are AC, AB, ACD. ABD. ACDB, and finally ACDE.
  6. There is a difference. The arguments about heavier than air flying machines, like may similar arguments, were arguments based on ignorance of the science. The theory with regard to light speed has implications that have been tested and found to be correct, even though nobody has propelled a rocket to light speed. Einstein's predictions have been tested in so many ways and found to be correct to such an extent that the preponderance of evidence suggests he was right.
  7. Being alive is dangerous. What value is there in living if one cannot enjoy life in the manner they prefer, within the bounds of behavior permitted by society?? Total Deaths in 2018 were over 2 million. Motor vehicles are a minor component of the risk of living.
  8. Speaking as a licensed HIgh School math teacher I would say no-- not something we should teach in High School. Benford's law is indeed very interesting, but the High School math curriculum is focused on continuing the development of math skills started in lower grades, in a building block fashion, in order to prepare the student for post-HS education. Pre-Algebra, Algebra, Geometry, Algebra 2, pre-calc and sometimes early stages of Calculus. That is, we are still in the process of building connected competencies-- one topic building on the previous. Benford's law and its implications is pretty much outside the things that have to get done in High School. The amount of material to be mastered is very large and difficult to do as is-- I would not want to add more.
  9. "The theory claims, and the article deduces from empirical knowledge", which is stated in the link, involves scientific thought, but does not prove anything, particularly since the authors have no proof for the timelessness they theorize occurs at death. It might be true, and might be of some benefit in understanding what a person goes through at death, but it is not proven. As such, its a significant stretch to say it is supported by science. The idea that a person might experience some feeling attributable to heaven or hell at death is not new (pleasure or regret about how one lived one's life)
  10. Pure vegetable oil is usable in diesel engines. That does require oxygen (as noted by Sensei). Ignition under those conditions is achieved a t 15-120 atm. For ignition or decomposition without oxygen it will depend on temperature as well as pressure-- so there is no single correct answer. While I do not know for certain. I suspect that since the oil is essentially not compressible, it will not significantly heat up as it is compressed and therefore high pressure alone will neither cause it to ignite nor decompose.
  11. Color codes for resistors: Bad Boys rape....... Totally out of place today and I would not repeat it now-- but it got me through my EE courses 54 years ago.
  12. I don't think the number of people represented is a direct issue. That is, I don;t think it matters if a district is 750k or 120 k as long as they are all the same population. But-- the disparity in district populations and the gerrymandering are issues. I would love to see some simple-minded criterion for districts that would minimize gerrymandering, but I'm not sure what it should be. "All districts shall consist of a single rectangle of sufficient size to encompass x people?" I suspect this might be like th famous problem of how to draw a map in different colors without having two adjacent areas the same color.
  13. OldChemE

    NRA dissolvement

    I must have worded things badly. What I meant was that they have NOT been seeking to solve the problems, whereas, they probably know the technology best.
  14. OldChemE

    NRA dissolvement

    I very much agree the leadership of the NRA should be held accountable for any provable acts along the lines of those charged. As a gun owner, I want the Second Amendment to remain, but have long felt that the organizations that know gun technology best (Manufacturers and the NRA) should have been working with government to solve the problems instead of blindly fighting everything. So-- I hope this lawsuit will lead to some positive results.
  15. Good summary. Having just recently retired from teaching I see many challenges here. Certainly, until now, online learning has been underutilized, but in some areas where it is used it is not used well. Case in point is Math. Quite a number of schools now do online instruction in Math, but the success rate has been uneven. I suspect the issue is that online systems cannot always detect why a student gets a wrong answer and provide the correct guidance (making students do math on paper and reviewing the actual paper is a very important part of math instruction). But-- there are efforts to overcome these type of issues and COVID has given us the impetus to take on the challenges. More to the point of the OP-- I think the answer is that education is being changed. We are very, very, lucky that the development of online learning was already well underway before the virus arose. I do not, however, think we will do away altogether with physical schools. Socialization is an important part of education, along with activities like art, music, performing arts, and similar things that do not so easily lend themselves to online studies.
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