To date, I think the only way you get one of these is to design, build and test it yourself.
Though, I'll be in Dubai in less than 3 weeks' time, so I'll see if I can pick one up while I'm there.
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To date, I think the only way you get one of these is to design, build and test it yourself.
Though, I'll be in Dubai in less than 3 weeks' time, so I'll see if I can pick one up while I'm there.
Up to 2:30, he's just hovering, and I'm thinking, what's the purpose of adding the wing, I wonder.
If it's a real airfoil, he'll get at least 10x more lift from the wing than from hovering on the engine thrust.
Then woosh. Off he goes.
Groooovy man. Stare at the centre until the video ends, then look at your palm.
https://www.youtube.com/watch?v=QzEENtz4bZY
C'mon, eyes!
I'm trying to do science, here!
Bleary-eyed, running on 5 hours of restless sleep on the train ride to Chicago.
Got a good breakfast in town, and some coffee and am now sitting on airport wifi waiting for a boarding call.
TSA seems much less of a hassle than it was a couple years ago. That's nice.
Made it Zurich. I sent $18 on 2 coffees at Starbucks in the airport, here. Ouch.
Airline food is absolutely gross. I def. recommend bringing your own food for long flights.
Seems like everything they were serving was trying to be some kind of weird. IDK what's up with that.
Like: who puts large chunks of watermelon in a salad?
Anyway. Airports are boring. At least Zurich has a couple smoking lounges.
For that kind of money you could get 1.5 Lovey Dovey massages (also known as Ong Fantasy Camp).
https://www.youtube.com/watch?v=NSzuBn-Pw-k
1/4. This is how we're all going to die. Who'da thunk it?
https://www.youtube.com/watch?v=XkYGt70bC6I
4/4 (maybe it's not all bad).
https://www.youtube.com/watch?v=t1PzqP-oolc
It has been said before: if we're going to strategically reduce the world's population, there's no better demographic to get rid off than cruise ship passengers... and CPAC attendees. The more I learn about coronavirus, the more I'm warming up to coronavirus!
I haven't read the Quran before, but I heard it's pretty much like the Bible.
Question: If there's four horsemen to the apocalypse in the Quran, what has disease been replaced with so that one can safely lick a shrine?
Follow-up Q : In the Bible, two of the horsemen are pestilence and famine. Don't these kind of go together, like the locusts eat the crops then everyone starves? So those really should be classed as one horse with delayed effects. We need a new edition of the bible I think.
Best thing I've seen on COVID-19 so far.
https://www.youtube.com/watch?v=E3URhJx0NSw
Back from the vacation.
Dubai is simply amazing. I def. recommend.
You can spend whatever you want in Dubai. Food is cheap. Transportation is cheap. Options are endless.
Unfortunately, no gambling, and FTR was behind a wall so I couldn't keep up, here.
And the sun is really pissed off about something, there.
There are an infinite amount of numbers that have the number 9 in it, and an infinite amount of numbers that don't have the number 9 in it, but statistically, 100% of numbers have the number 9 in it.
True story.
There are 2 ways to write most rational numbers, in any base.
In base 10, it involves reducing the final digit by 1, and adding an infinite string of 9's after it.
0.99... = 1
They are 2 names for the same entity.
Similarly,
1.99... = 2
0.0499.. = 0.05
Rational numbers that don't work are numbers that are already infinitely repeating, but don't contain a 9.
Any integer over 7 or 9 will do this.
And 0, of course.
IDK what statistics you're using where you can find an infinite number of counter-examples to your claim of 100%, but still make the claim.
There are, of course, irrationals that do not contain any 9's.
The point is that the smaller infinity is infinitely smaller than the big infinity. It might be better to say *nearly all* numbers have a 9 in them. (base ten of course). The amount of numbers that don't have a 9 in them is so insignificantly small compared to the number that do, that it is, for all practical purposes, zero. Yes there are an infinite number of counter examples, but it's still essentially 0% of all numbers.
To know a percentage one value represents out of another you have to be able to divide by the entire set of values.
If you try to divide by infinity you get:
NaN
So you're little story is nice and all, but...in this universe we follow the laws of mathematics.
Mathematics becomes a bit blurry when we start talking about infinities. It's ludicrous to say one infinity is bigger than another, but at the same time entirely logical.
Yes, because infinity isn't a number, it's a concept of unendingness. So you can't divide a number by a concept and get a number back out of it. Mathematics isn't prepared to handle an object like 1/bigness.
We usually get around this by using limits.
1/x -> 0 as x -> infinity
or
e^x -> infinity as x -> infinity.
But there are times in mathematics and physics when direct evaluation of multiple infinities comes up. We have a problem to solve where we end up with one infinity over another infinity, and we need to know whether or not that fraction converges or diverges.
This means sometimes we have to make physical sense of infinity/infinity and that's when things get really weird, IMO.
Like the sum of all positive whole numbers being equal to -1/12. Is that statement, strictly speaking, true? IDK. It can be shown in some formalizations to be a logical answer to the question of what you get when you sum all the positive integers... and it's the fact that you're summing an infinite series that causes all the commotion. That and the fact that the result seems an obvious troll on multiple levels.
This post gave my brain the fuzzy tingles-- until this last paragraph. I feel like I walked in in the middle of a conversation and missed pertinent info. How is it that the sum of all positive integers could possibly equal a negative fraction? Is there any significance to -1/12 in particular?
I saw something about it an as best I can recall, it's a mathematical absurdity based on how you interpret how to solve an infinite fraction. It can be best simplified by saying 1+2*4=12, when in fact it is 9 (order of operation), but that simplification doesn't do justice to the complexity of solving infinite fractions.
I might be wrong though, can't remember it clearly.
I am wrong. It's based on the assertion that the solution to the infinite sum 1+1-1+1-1+1... is equal to 0.5, which is not true, even though it seems it is true. It's a mathematical magic trick.
Yeah, it seems like 1+1-1+1-1+1... is just a nonsensical way of trying to express a probability. It's like saying the result of a coin toss is teads.
The thing with these infinite sums and infinite fractions is that they are actually extremely useful at expressing irrational numbers in surprisingly simple ways, for example 1+1/(1+1(1+1(1+1(1+1... is equal to the golden ratio. You can never complete this sum, no more than you can express the golden ratio in decimal form accurately, but you can close the brackets at any given time, solve the equation, and the solution converges to the golden ratio the longer the sum is. But once you actually understand that sum. it's remarkably simple. We only used the number 1, and we got the most irrational number of them all.
Continued fractions were much more useful in days before pocket calculators.
The value of 22/7 for pi comes from using continued fractions.
Knowing a number, you can find a fraction approximation using a simple set of rules.
for pi = 3.14159...
Isolate the leading digits before the decimal.
pi = 3 + 0.14159...
Now, we can stop here by ignoring the decimal part.
pi = 3 is a fine approximation for quick, back of the envelope calculations.
For a better approximation, we then invert the decimal part.
1/0.14159... = 7.06251...
So now
pi = 3 + 1/7.06251...
Isolate the leading digits again
pi = 3 + 1/(7 + 0.06251...)
Ignore the 0.06251... 'case we're making an approximation,
pi = 3 + 1/7 = 22/7
Since that remaining part we chopped off was "small" 0.06 << 1 we have a "good" approximation.
Better to say we have a good approximation for the work we put in.
Not all numbers will give a good approximation after only 1 step.
Solving the fraction back to a single number over a single number, and not a continued fraction, can be tedious.
If we want to keep going with pi
pi = 3 + 1/(7 + 1/15.99659...)
pi = 3 + 1/(7 + 1/(15 + 0.99659...))
we could stop here, but the 0.99 part is not "much less than" 1, so our approximation wont be much better than it was in the prior step. (It would be 333/106, just to state it.)
pi = 3 + 1/(7 + 1/(15 + 1/1.00341...))
pi = 3 + 1/(7 + 1/(15 + 1/(1 + 0.00341...)))
Ignore the 0.00341 'cause approximation, and it's the "much less than" 1, so this is a good stopping point for our effort.
working it back to a "normal" fraction:
pi = 3 + 1/(7 + 1/(15 + 1/1))
pi = 3 + 1/(7 + 1/16)
pi = 3 + 1/(113/16)
pi = 3 + 16/113
pi = 355/113
Note 22/7 is accurate to 2 decimal places.
The "bad" approximation would be 333/106, accurate to 3 decimal places. Better, just not much better.
The 3rd approximation, 355/113 is accurate to 6 decimal places. So really worth it for the effort to take that extra step (if you needed the accuracy, that is).
When I was a kid, I memorised pi to ten digits because I figured it was more useful than remembering the different approximations.
This, besides being entertaining to watch might be the best practical introduction to how a refrigerant cycle works on YT right now. If you're remotely interested in that stuff, I can highly recommend it.
https://www.youtube.com/watch?v=z_Ti4GP0ntE&feature=youtu.be
And it's efficient because you only have to remember one less number than if you were to remember Pi to the 6th decimal place.Quote:
The 3rd approximation, 355/113 is accurate to 6 decimal places. So really worth it for the effort to take that extra step (if you needed the accuracy, that is).
Exactly my point. I really did find it silly that people will remember specific fractions to approximate pi, instead of just memorising the number to a sufficient level.
I know pi to ten digits, so I don't need to know any fractions that approximate pi. If for some reason I ever need to know pi to a greater degree of accuracy than I know, then that's what google is for.
355/113 is stupid anyway. You either need to write out a long calculation, or use a calculator. If it's the latter, there's probably a pi button. Use that instead. If it's the former, it's a lot more work than simply knowing the number.
fwiw I have always pretended Pi was 3 and it has not failed me so far.
If I can't be bothered to use my phone, I'm only doing approximations anyway.
Oh... does anyone have a favorite Android calc. I use the "hiper scientific" when I need features that the stock one doesn't have, but I'm not very excited about it.
It's a reasonable enough approximation for people who give no fucks.
Ridiculously overqualified life support manekin maker:
https://youtu.be/FH9U7e2AkNo
I hear a NZ accent: I start laughing before I know what the joke is.
Aussie and NZ sound the same to me: stupid.
And this from a guy who grew up around people who spoke cowboy.
Aussie and Kiwi have their differences. Kiwi sounds a bit like Aussie + South African. While Safricans pronounce their nation as "Sarf Efrica", a Kiwi might say "Sarf Ifrica". An Aussie pronounces the A correctly though.
Also, Aussies say "fuck", "dickhead" and "wanker" a lot more than Kiwis.
If they say "you're a wanker", it's Oz.
If they say "you're a winker", it's Kiwi.
If they say "you're a wenker" then stab you, it's Saffer.
Pi = e = 3
https://i.redd.it/63avij439wr41.jpg
This will melt your brain.
https://twitter.com/DrGBuckingham/st...07820754403328
^ that's cool
Fuck all the damn twitter posts lately.
Eat a bag of wet ducks, the lot of you.
To no one's surprise, we have found evidence of widespread cheating on the first at-home exam we've given during quarantine.
The average score from over 530 students was a 92%. There was a ridiculous number of exams which scored 100%.
At least one exam blatantly copy/pasted answers using explanations that we did not cover in lecture and which are not in the text book.
Made it very easy to find what they copied from a simple google search.
Flatten the curve?
Seriously, what do you do with that? Throw the exam out? You can punish the people who obviously cheated, but other than that, I don't see how you can fairly handle it.
Our uni is going to online exams, where the students get to choose two hours during a 24 hour window in which to write their exams. Even with long-answer questions I suspect we'll have similar outcomes. Looking forward to that shitshow lol.
Pi = e = sqrt(G)
Because we're talking about complicated physics questions, requiring understanding of the specific interactions at play.
It's like... I don't care if a student googles the solution to an integral. I do care if a student googles which integral needs to be solved.
A computer can do the rigorous logic stuff, but a human needs to evaluate the situation, pare the information down to the essential bits, determine what is constant and what is changing, and apply the physics concepts to predict an outcome.
A google search will only answer an already answered question, but it can't tell you which specific question needs to be answered.
We're handing the students manicured, "easily" solved questions to test their personal understanding of the concepts at play. Of course you can google answers to such simple questions. So can your boss. That's not what they hired you for. If it is, it wouldn't require a college course to learn it, and you wouldn't get paid much more than minimum wage to do that job.
Our department holds the opinion that our tests are fair, the questions are hard, and not all years will see students of equal capacity.
The grades should be curved only when there is a flaw in the test itself, and not due to student performance being unusually high or low.
This is thrown out the window for physics labs, because student graders are more erratic than professors when grading long-answer questions.
It's like detective work. You find a known cheater, you use that form of cheating to look for other cheaters.
There's the one I mentioned, which was just sloppy. Then there's finding multiple exams with identical solutions on some problems.
That's not conclusive, because of the nature of math, but it is often a strong indicator that students were working together, if not accidentally by copying the same thing from a 3rd party.
E.g. there's a web site called Chegg that hosts exam solutions uploaded by members. We know for a fact that at least one student uploaded the exam answers to our exam during the exam time. Chegg requires payment for membership, so presumably have credit card information about their users. For some reason, they work with college deans to uncover cheating... WHAT? Isn't their entire business model to enable cheating? Whatever.
So we sent out an announcement that we know there was cheating. Any student who comes forward and admits what they did, and cooperates with the professors will only be given a 0 on exam 2, with no further consequences. Any student found to be cheating who did not come forward on their own will be given a 0 and reported to the office of academic integrity, with a permanent mark on their record.
For many of our students, that mark will eliminate their top 10 choices of graduate school.
For students who are not planning on going on to grad school, it hardly matters. Only if they get multiple infractions with the university will there be anything other than a reprimand.
That 24 hour window is what we think made the problem so bad.
We were trying to accommodate students in China or elsewhere in distant time zones, but it bit us in the backside.
We're only allowing a 4 hour window for the final exam, and if that puts it at some weird hour of the morning, then it is what it is.
You know what, I thought so too, but then I googled it, and Wikipedia says it's G: https://en.wikipedia.org/wiki/Gravitational_constant
https://i.kym-cdn.com/photos/images/...66/573/262.png
oh g is the one for earth... got it.
Yes, because obviously no-one will tell their friend what the questions are in the 2-22 hours between when each writes the exam.
Our system is a bit different in that we don't have midterms, our semester ended right after the lockdown, coursework is online anyways (though everyone was given a 3 weeks extension on cw college-wide), and so the final exams is going to the first attempt at doing something like this. And it's going to be a month of crash and burn so spectactular it won't even be funny.
We don't hold the position that student skill fluctuates much from year to year. If there's a sudden 20% increase in final exam scores, I have no idea how they will handle it, but I'm pretty sure they won't just let it be.
I didn't explain it well.
The exam will be posted online at 6:30 PM St. Louis time, and all exams are due by 10:30 PM St Louis time.
All students take the exam concurrently.
Yep. I'm trying to reach out to other departments and institutions to see how they're handling things.
It's a new experiment for the entire world, but we're in a good position to adapt quickly. Open communication and copy/pasting of teaching ideas between universities is a long-established tradition.
Yeah... I wasn't there to suggest that they were having an altogether misguided sense of human nature when that decision was made.
I really don't think the faculty appreciate the amount of stress the students are under and how little the students like the material.
Introphys is a required course for a lot of science majors, and not many students like physics as such.
Tell anyone to do something they don't want to do, and tell them that their performance will have long-term ramifications on their future, and what do you expect?
I expect widespread cheating to the extent that it can be gotten away with and no less.
If I was in their place, I'd 100% have googled my answers to at least verify I didn't make some big mistake. The thing is that I was always smart enough to never directly copy, and to actually leave in mistakes I felt I would have made, anyway.
E.g. when calculating the lift force on a hot air balloon on one HW problem, I solved it, then googled the answer. I was way off. I'd forgotten to account for the fact that the hot air was filling a volume that was not a vacuum, and the lift force of the hot air has to also lift its own weight in addition to the balloon and gondola's weights. I figured that was a mistake that wasn't even on my radar as something to consider, so I left it in, and took the hit on the grade.
Good luck catching a cheater like that.
No, it opens at 6:30, and they have 4 hours to work it. I don't think I said it's designed to be a 2-hour exam, but it is.
It is still flawed, obv. but we're stumbling into new territory, and trying to figure it out as we go.
Yeah well, my uni has effectively made every final an open-book exam where you have somewhere between 2-22 hours to complete it, depending on who you know and when they started.
Almost all of the exams were written to be closed-book, 2hr max.
If using google is sufficient for a physics exam, I want a fucking job as a physician.
I think the big upside of a university is that you can directly ask someone if you're getting stuck, and tests show you what you need to focus on. In terms of quality of education, you can find amazing stuff on YT... A lot of universities are uploading their lectures. And it's often not the universities that even have the most useful material. The standard electrical engineering education is stunningly inefficient. Ok, I get it, you need to be able to apply Ohm's Law and Kirchoff's Law, but every EE 101 course goes Black Lodge on that shit. resistance networks with 3 opposing DC sources: "calculate the current through point J"... No don't do that! Throw it in the trash! It doesn't do shit!
Nobody's going to pay you for that!
This channel is a prime example of why YT rocks: https://www.youtube.com/channel/UCk0...zGig-rSzkfCjMw
I think the upside of a college education is that you have a team of experts lighting a fire under you to keep you moving along at a rapid pace.
Anyone could buy all the textbooks and work their way through them, doing the homework problems as they go. It's just... very few people have the self-discipline to do that, even for the subjects they're immediately interested in. They're never going to do that with the elective courses and introductory theory courses.
Introduction courses (101 courses) are broad but shallow surveys of a field of study. They show the overall landscape and how various pieces of that discipline fit together in a big-picture way. They don't have specific training for applied sciences.
They're more like grammar classes. Here's all the important words you're going to hear for the next 3 - 4 years, and you need to be immediately familiar with them in a deep and personal way if you want to learn those deeper applications quickly.
(It's not that you will ever need to calculate the current through a complicated junction using Kirchhoff's Law. It's that you need to see a junction and immediately have Kirchhoff's Law somewhere in the back of your mind. IMO. Not an EE.)
My point is that those are the things people skip, even when they have some self-motivation to learn college level skills on their own.
Most of our students don't like physics and don't appreciate, now, that they have to spend this year learning it. However, they will appreciate it in the long run when their upper-level classes throw these fundamental concepts around like they're talking about the weather.
The benefit of being on a college campus at a major university is that in addition to that fire under you, you have a vast support group of libraries, labs, administrators, faculty and staff, not to mention the peer-support networks inherent in the structure.