Regarding the Website's Content
Hi Guys,
Take it from a guy who is completely confused when it comes to electronics.
I have tried reading textbooks, Simple Radio Shack Electronics books and even view videos on how electronics and electrical proprties such as current, voltage and resistance function. I have never been able to understand and retain the concepts, because it doesn't make sense to me. I'm not understanding the fundimentals regarding electricity. The example of water flow through a hose or dumping water from a higher potential to a low potential has never really cleared things up or sink in completely. The direction of flow from negative to positive hasn't helped to clear things up much either.
I have too many questions. How does DC and AC live in the same circuit? If you have AC charging a circuit, what path does a DC signal take? Even when I look at a simple single-ended design like the Zen amp, it get confused as soon as everything converges at the output.
I happy that there is someone out there that knows what they are talking about to care enough to try to explain it to a person like me. So it sounds a little negative. So what? Some people around here, even when sounding positive, they come off very negative. Myself included.
In any case, I hope I learn something from this site because I'm tired of building stuff and not really knowing how it's working. I would love to someday look at a circuit and just say, " Yeah, I get it." I bet that once I undestand it, I could teach it to anyone. I would love to be able to do that also.
My 2 cents. Thanks.
Vince
Hi Guys,
Take it from a guy who is completely confused when it comes to electronics.
I have tried reading textbooks, Simple Radio Shack Electronics books and even view videos on how electronics and electrical proprties such as current, voltage and resistance function. I have never been able to understand and retain the concepts, because it doesn't make sense to me. I'm not understanding the fundimentals regarding electricity. The example of water flow through a hose or dumping water from a higher potential to a low potential has never really cleared things up or sink in completely. The direction of flow from negative to positive hasn't helped to clear things up much either.
I have too many questions. How does DC and AC live in the same circuit? If you have AC charging a circuit, what path does a DC signal take? Even when I look at a simple single-ended design like the Zen amp, it get confused as soon as everything converges at the output.
I happy that there is someone out there that knows what they are talking about to care enough to try to explain it to a person like me. So it sounds a little negative. So what? Some people around here, even when sounding positive, they come off very negative. Myself included.
In any case, I hope I learn something from this site because I'm tired of building stuff and not really knowing how it's working. I would love to someday look at a circuit and just say, " Yeah, I get it." I bet that once I undestand it, I could teach it to anyone. I would love to be able to do that also.
My 2 cents. Thanks.
Vince
Last edited:
wbeaty: I just had a looked at your website. I am in total admiration of what you are trying to do. I am now retired, but I have mainly taught high school physics, and have seen these misconceptions in science books and felt totally unable to do anything about it.
You are a chemist. Maybe you could help the world by coining a better term for "oxidation" and "reduction". I always felt that these terms somewhat confusing.
SY: People that write entrance examinations for professions should update their education. Maybe the magic might return.
I have also struggled with exam writers setting exams with "type" questions that force a teacher to "teach to the exam".
I had a few years when I was able to teach high school physics without external exams hovering over me, and during these years I had a greater proportion of my graduates enter the physics faculty than I did when the exams were back.
You are a chemist. Maybe you could help the world by coining a better term for "oxidation" and "reduction". I always felt that these terms somewhat confusing.
SY: People that write entrance examinations for professions should update their education. Maybe the magic might return.
I have also struggled with exam writers setting exams with "type" questions that force a teacher to "teach to the exam".
I had a few years when I was able to teach high school physics without external exams hovering over me, and during these years I had a greater proportion of my graduates enter the physics faculty than I did when the exams were back.
Last edited:
if generating lift the wing is "throwing air down", the lift force comes from changing the momentum of air mass flow
Newton's Third Law of Motion
near a boundary, the air deflected by the wing bounces off of the ground and the air flow is the sum of the deflected and reflected flows
"ground effect" becomes improtant in modifying the lift/drag when the wing is < the wing chord length from the boundary
Newton's Third Law of Motion
near a boundary, the air deflected by the wing bounces off of the ground and the air flow is the sum of the deflected and reflected flows
"ground effect" becomes improtant in modifying the lift/drag when the wing is < the wing chord length from the boundary
Last edited:
If you are struggling with the concepts then precise definitions probably won't help because they will almost certainly bring in too much detail too quickly.
I first learnt some real understanding from Scroggie's "Foundations of Wireless". There were many editions of this, originally by Sowerby, more recently by Amos. Buy any version you can find and read through it slowly.
I first learnt some real understanding from Scroggie's "Foundations of Wireless". There were many editions of this, originally by Sowerby, more recently by Amos. Buy any version you can find and read through it slowly.
When I first learnt about it "oxidation" involved oxygen. Then it was generalised to include things like chlorine. Later it became more abstract and had something to do with donating electrons? (It was a long time ago) "Reduction" was the opposite.
This seems like a sensible order in which to approach a concept. A pedant would (presumably) wish to confine 'oxidation' to reactions involving oxygen (so we would have to find a new name for analogous reactions with chlorine), or go to the other extreme and define it in terms of electrons (and so confuse people just beginning to learn chemistry who don't yet have a good grasp of what an electron is).
This seems like a sensible order in which to approach a concept. A pedant would (presumably) wish to confine 'oxidation' to reactions involving oxygen (so we would have to find a new name for analogous reactions with chlorine), or go to the other extreme and define it in terms of electrons (and so confuse people just beginning to learn chemistry who don't yet have a good grasp of what an electron is).
I like mnemonics. LEO- loss of electrons is oxidation.
My mnemonic for resistor color codes is in thoroughly bad taste and will not be given here!
My mnemonic for resistor color codes is in thoroughly bad taste and will not be given here!
Its been a few years since I taught chemistry, but I started off with electrons and protons before I introduced any reactions.
I believe the Bernulli effect does not rely on "throwing air down", it is a result of the velocity of the flow above the wing being faster than the velocity below it.
I would say that resultant "throwing air down" is an effect, not a cause.
If I remember correctly, ground effect is a result of the pressure wave caused by the wing moving through the air and displacing it at the leading edge of the airfoil...it has been 3 decades of course...
Cheers, John
Stick and Rudder: An Explanation of ... - Google Books
Look especially at the section entitled "Forget Bernoulli's Theorem."
Look especially at the section entitled "Forget Bernoulli's Theorem."
I sometimes wonder if a greater attempt should be made to post circuits on the wiki pages, with accurate, concise information and discussion, leaving out the personal attacks that seem to blow up all too often in some of the very long threads.
I guess I need better advertizing on link relevance
Newton's Third Law of Motion is a NASA site
"Newton's Third Law Applied to Areodynamics"
lots of great links, apps - all except the "Kids page" which does the airfoil upper/lower speed/path length thing the rest of the site "debunks" - don't hire dumb tech writers to "simplify"
Newton's Third Law of Motion is a NASA site
"Newton's Third Law Applied to Areodynamics"
lots of great links, apps - all except the "Kids page" which does the airfoil upper/lower speed/path length thing the rest of the site "debunks" - don't hire dumb tech writers to "simplify"
Wow.
I like the sentences:red hilite mine..
""Bernoulli's theorem doesn't help you the least bit in flying. While it is no doubt true, it usually merely serves to obscure to the pilot certain simpler, much more important, much more helpful facts.""
Written in 1944 by an economist who decided, mid-PhD, to learn how to fly. Sigh...
This kind of thinking is precisely the problem being railed about here. A complete and utter disconnect between how something works from a theoretical pov, and how the end user perceives and uses the technology. For most end users, what happens under the hood is not important. They don't know, they don't care, and the details are of no use. It either works or it doesn't.
I'm fine with that. There will be users who can never understand the principles, so why is it important for them to be forced to learn?
Cheers, John
Yes, you do. I would have missed that really neat link otherwise.
So, you mean dumb tech writers who did the airfoil thingy, or the dumb tech writers who debunked it?😕
I played with that airfoil app a bit. Really neat!!!
Used the symmetrical one...the text mentions how the longer path/faster velocity shtick was incorrect because a symmetrical airfoil can produce lift by varying the angle of attack..."case closed"..
But then, if you take the symmetrical airfoil, lift it to 14.7 degrees, producing 900 plus pounds of lift...and then measure the velocity of the air above and below....gee..90 mph below the foil in general, 170 mph peak above, with consistenly higher readings along the entire upper profile..
But pay no attention to that man (bernouilli) behind the curtain...
Sheesh, kids get the hi tek stuff, college to grade skool? pffft.
Cheers, John
Langewiesche's point was that Bernoulli's theorem is true, but not particularly useful for understanding why wings work. Two minutes in a moving car with your hand out the window will demonstrate why Langewiesche should be taken seriously if you want to gain useful understanding.
Comprehension of the information given. J
I did not want to comment, however there has been many ideas on learning it’s so tied up in paper work that even teachers cannot understand how to teach without being ridiculed because it does not meet current ideas.
Quote everyone has a learning style and the subject should be taught in as many different ways as possible to cover each learning style.
The bottom line is, how can anyone understand a concept taught by words that they have no understanding of. This is supposed to be covered by levels 1/2/3 etc to get an understanding of basic concepts.
Often it is required to create a nonsense example to communicate an idea. This is not wrong if the idea creates a situation of understanding that can be understood (even if incorrect) that can then be modified to the correct information after the initial removal of barriers.
Eg Algebraic sums of current at a junction must equal zero.
Remove barriers: current at a junction (screw terminal with two cables connected to it)
Junction = screw- current into screw is equal to current out of the screw.
If we take the screw as the reference point.
If the current is 1 unit in this is + into screw 1 unit out is – from the screw if we add the values together then +1 in added to -1 out equals zero.
Then compare to :
http://www.physics.uoguelph.ca/tutorials/ohm/Q.ohm.KCL.html
No futher comment.. J
I did not want to comment, however there has been many ideas on learning it’s so tied up in paper work that even teachers cannot understand how to teach without being ridiculed because it does not meet current ideas.
Quote everyone has a learning style and the subject should be taught in as many different ways as possible to cover each learning style.
The bottom line is, how can anyone understand a concept taught by words that they have no understanding of. This is supposed to be covered by levels 1/2/3 etc to get an understanding of basic concepts.
Often it is required to create a nonsense example to communicate an idea. This is not wrong if the idea creates a situation of understanding that can be understood (even if incorrect) that can then be modified to the correct information after the initial removal of barriers.
Eg Algebraic sums of current at a junction must equal zero.
Remove barriers: current at a junction (screw terminal with two cables connected to it)
Junction = screw- current into screw is equal to current out of the screw.
If we take the screw as the reference point.
If the current is 1 unit in this is + into screw 1 unit out is – from the screw if we add the values together then +1 in added to -1 out equals zero.
Then compare to :
http://www.physics.uoguelph.ca/tutorials/ohm/Q.ohm.KCL.html
No futher comment.. J
As you may not have read my later post, you probably do not yet realize I concur with your statement.
The hand out of window example you cite is one everybody can recognize. It also unfortunately for pilots, does not explain what a stall is. A simplistic view of mass flow diversion does not explain the sudden loss of lift.
Cheers, John
Stall is best understood from a velocity perspective, IMO. That's tough to do with a car since your hand isn't changing the car's velocity in the same way that angle of attack changes the airplane's velocity. 😀
It is possible to stall at a constant velocity by exceeding an angle of attack. Yet, the concept of mass flow diversion doesn't explain it well.
A hand out the window is certainly not optimized to show how a profile shape can provide lift. That application on the nasa site does indeed show how even a symmetrical one can change the velocities over and under as a result of angle of attack.. The problem with using the angle of attack to produce lift however, is when the flow over the top transforms into violent turbulence and loss of lift.
Simple diversion of massflow doesn't predict stall.
Living close the the edge when travelling several hundred miles an hour, a mile or two above terra firma is not my idea of fun.
Cheers, John
- Status
- Not open for further replies.