Jump to content

Carrock

Senior Members
  • Content Count

    575
  • Joined

  • Last visited

  • Days Won

    2

Carrock last won the day on December 10 2018

Carrock had the most liked content!

Community Reputation

95 Excellent

About Carrock

  • Rank
    Molecule

Profile Information

  • Favorite Area of Science
    physics

Recent Profile Visitors

6394 profile views
  1. Gets worse than that. Sometimes in the same system work done in e.g. charging a capacitor is regarded as positive, while work done discharging a capacitor is, er, positive. You can then say (e.g. from https://www.allaboutcircuits.com/textbook/alternating-current/chpt-6/q-and-bandwidth-resonant-circuit/ ) You can actually buy a power buildup cavity using the same general idea. From Wiki It seems like you could put in 10mW and get 1 MW out. Apparently the concept of imaginary power or reactive power (which is not available for continuous work) is not used here; 'stored power' is just power. It's rather like saying torque is energy because the units are dimensionally the same. There's a simple definition of Q to avoid this confusion* Q(omega)= omega*(maximum energy stored/power loss) *My confusion anyway - there must be some rationale to the "stored power is not energy" concept.
  2. Could the same amount of power as is in the (I presume resonant) cavity be continuously removed from it and it still be a buildup cavity? If not, some of the power is no more available than the power of a swinging pendulum as it converts kinetic energy to potential energy and back to kinetic energy again. I might try to convince a keen equestrian non-scientist that going for a walk to warm up is more eco friendly than sitting in front of a four horsepower heater. He might disregard my suggestion as horsepower is not electrical.
  3. Maybe misleading? I think you're referring to what engineers call reactive or imaginary power, which is related to stored energy and is measured in volt-amperes, not watts.
  4. Croatia went in for extreme lockdown but it also seems to be doing a lot of testing and presumably contact tracing etc. IMO the most important thing NZ and Croatia have in common is they first treated Covid as a serious problem less than a month after their index case. So many other countries seem to have decided to wait and see if the predictions by WHO etc of a major epidemic were correct before doing anything. (CharonY's comment also relevant and helpful.)
  5. I chose NZ because it was well documented (see the length of the wiki article). I don't believe any country could pretty much eliminate cv without "establish effective work procedures, organize tracking teams, educate population." No need for a major expansion of hospital capacity in NZ though. Cynically, there's one very good reason it's unlikely NZ leaders will allow a resurgence. From 13th April:
  6. Time for a mention of New Zealand and its coronavirus on this forum... After 21 deaths and with 65 still active cases it is down to level2 lockdown i.e. just maintain social distancing. The country was put into full lockdown less than a month after the index case. https://en.wikipedia.org/wiki/2020_coronavirus_pandemic_in_New_Zealand https://www.cnbc.com/2020/05/05/how-new-zealand-brought-new-coronavirus-cases-down-to-zero.html
  7. I suppose the real problem is not knowing in advance if the research is utilitarian. e.g. what practical use could anyone around 1900 expect from investigating black body radiation? My favourite example is Faraday's apocryphal responses to Gladstone's question "What use is electricity?" "What use is a new born baby?" or "I don't know, but some day you will tax it."
  8. Yep. In 1988, against orders, the captain of the USS Vincennes was in Iranian waters when an aircraft approached the vessel. The untrained crew mistook the Airbus A300 for a military aircraft. An easy mistake to make and it didn't damage his career. From https://en.wikipedia.org/wiki/William_C._Rogers_III X-post with Migl.
  9. +1 for longest link I've ever seen. I should stay in more. 😀
  10. Well.... From Wikipedia while from Azo materials
  11. From https://www.bbc.co.uk/news/science-environment-52297058 This seems to be the first evidence for neutrino CP violation. I don't know how significant the results might be. The original paper is free to read in Nature.
  12. Really? The only relevantly rated high spec starter lead-acid car battery I've seen was 40AH 160 amp crank current for 2 minutes at -20deg C i.e. about about 5AH before the battery needs to depolarise and cool; before another 2minutes of cranking. Your jump starter is 8AH; the 800 amp crank current is not needed here but makes the battery sound better. X-posted with Ghideon.
  13. Factcheck alert: From Grauniad tabloid: size matters, but not as much as content: Philippa Clarke said
  14. Diamond is best but beryllium oxide is excellent for this. It is extremely toxic but it seems it is being replaced by aluminum nitride. There are various other solutions - provide more information or look for how a problem similar to yours has been solved.
  15. This idea that e.g. some entities e.g. electrons can be/are in a superposition of states while others e.g. grains of salt can't be has been popular from time to time; sufficiently for experiment to rule it out. (I recall this but can't yet find a reference.) The basic problem is you would need some sort of physics to kick in as small QFT regime waves or whatever accrete and somehow become classical particles. https://en.wikipedia.org/wiki/Quantum_decoherence is interesting e.g.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.