Leaderboard

The plane crash involved a Boeing 737-800NG, not the MAX but a previous version with stable aerodynamics and no computer override. The plane was 3 years old and had been in for maintenance on Monday. And Ukraine has suspended all flights into the area, but hasn't grounded similar 737-800NGs. I personally haven't seen it, but there are reports of a video showing the plane coming down engulfed in a fireball, and wreckage photos show puncture damage from either engine failure and breach of blades, or shrapnel. The plane was at 8000 ft when contact was lost and it disappeared from radar, but the ground elevation in the area is over 3000 ft, and it had made a sharp left turn as it climbed out at less than 5000 ft relative to ground elevation. At this point it would have been close to the Malard missile launch site. Given the circumstances, this does not seem to be a technical issue, even if there had been enough time to do an investigation ( usually takes months ), and engine failiures do not result in that type of a crash. I would assume, until evidence proves me wrong,, that the plane was warned not to overfly the missile launch site, but was mistaken by Iranian air defenses as incoming cruise missile or possibly even MANPAD launched in error at a low flying target. I have also seen reports of the 63 Canadians being mostly students from the Toronto area. Seems Iran's 'insignificant' response may have led to some very serious consequences, and the 'fog' of war has shown up again. May all 180 passengers RIP.

One important point when we state the universe expanded from a miniscule finite point we are referring to our Observable portion of the universe. The remainder of the universe could be infinite or finite. We simply do not know. Think of our observable portion as the region of shared causality with regards to the BB. It is as mentioned expansion from a hot dense state with which our entire observable portion resides within that portion. You cannot look at any direction and state the BB exists that away. It is all around us and completely surrounds us.

It is very disingenuous to ask a question then assert the answers are wrong.

Did you not already explain what is wrong with it in your first sentence?

Most students I've encountered find a table to be quite helpful with these questions, though this is probably not a complicated enough example to really warrant it. Your answer is fine.

The only (well tested and confirmed) theory we have for black holes is General Relativity. This says that all the matter that enters a black hole is compressed to an infinitely small singularity with infinite density. Therefore, this theory is almost certainly not correctly describing what happens. A theory of quantum gravity might tells us what happens to the mass inside a m black hole - although we can probably never confirm that directly. Unless it changes how we view the event horizon; it might turn out to be "porous" or not really exist or something. (String theory describes the inside of a black hole as a "fuzzball", but until we have some way of testing string theory, we have no idea if that is any more realistic: https://en.wikipedia.org/wiki/Fuzzball_(string_theory)) Both gravity and time dilation (and length contraction) are ways we perceive the curvature of spacetime. So it is not that gravity "affects" spacetime; but gravity is spacetime. I think only in the case of something like a black hole (where there is a concentration of mass in one place). I don't think it is true for the singularity in the big bang model, because in that case, mass is always uniformly distributed throughout the universe. (I may be wrong. I often am!) In our current theories nothing can escape from the inside of a black hole. Jets are generated outside the black hole.

The simplest brute-force dividing algorithm in C/C++ would look like: int quotient = 0; while( dividend >= divisor ) { dividend -= divisor; quotient++; } int reminder = dividend; // subtraction failed "subtract divisor from dividend until dividend is greater than or equal to divisor". The number of repetitions on the loop will be O(quotient) The more sophisticated version could left-shift divisor prior subtraction from dividend. Each binary left-shift operation is multiplication by 2. At the same time value added to quotient should be multiplied by 2. (In binary numeral system left-shift is equivalent of multiplication by 2, move the all bits one position to the left and make room for 0 at the end for the least significant bit) So e.g. division of 1000 by 50 will look like: temporary_quotient = 1; 1000 > 50 (true) 50*2 = 100, temporary_quotient*2 =2 1000 > 100 (true) 100*2=200, temporary_quotient*2=4 1000>200 (true) 200*2=400, temporary_quotient*2 =8 1000>400 (true) 400*2=800, temporary_quotient*2=16 1000>800 (true) 800*2=1600, temporary_quotient*2=32 1000>1600 (false! We are using previous values and subtract it from 1000! i.e. 800 and 16) 1000-800=200, quotient += temporary_quotient (16) Repetition of entire procedure once again: temporary_quotient = 1; 200 > 50 (true) 50*2 = 100, temporary_quotient*2=2 200 > 100 (true) 100*2=200, temporary_quotient*2=4 200 == 200 (they are equal, end of the loop) 200-200=0, quotient += temporary_quotient (16+4=20) 50 * 20 = 1000 That reminds me that the single division operation in machine code of Motorola 68000 (Amiga 500, Atari ST) was talking over 150-170 cycles of cpu (running at 7.16 MHz) (unsigned integer div faster, signed integer div slower). So at max it could do just 7,160,000 / 150 = ~47,000 divisions per second.

Following MigLs conspiracy thinking comment, my brain started wondering if the plane was taken down by Russian using cybertech... The rabbit hole goes deep. Let's all work together not to let these unsupported speculations overwhelm our reason and rationality. And remember... the lizard men did it!

I saw about that third wave of missiles on at least 3 different news sites as well, yet I cannot find a single instance of it now.

Further to Mordred's point about apparent velocities and the effect of scaling on them... I can easily move the bright dot of a laser faster than the speed of light across the surface of the moon, by moving the laser relatively slowly here on earth.

Here is an interesting side note recessive velocity is based upon Hubble's law. The greater the seperation distance the greater the recessive velocity the formula is [math]V_{recessive}=H_OD[/math] So beyond Hubble horizon based on that formula the galaxies appear to be separating at greater than c. However that is an Apparent velocity and not a true velocity. In point of fact those galaxies move at the same speeds as our own Milky way. This brings a further side note expansion being described as greater than c uses the same seperation distance relationship. However per Mpc in every location the expansion rate is only roughly 70 Km/Mpc/sec this rate is actually decreasing even though the expansion rate based on the seperation distance to our cosmological event horizon is accelerating. So there is no violation of GR as recessive velocity is an apparent velocity and not a true velocity.

I feel this was a pretty smart move by Iran. We made a direct, in-your-face, significant attack which they would have felt required a significant response. At the same time, they seem to be saying "now let's let it go and get back to our normal way of doing things". Ball is in our court. Can Trump accept the proposal and possibly see this crisis end? Will he not accept because it would be bad for his base? Will he not accept because he is a megalomaniac? Personally I hope we don't respond in kind, but I don't know if that is something Trump will be able to do. He already drew a red line by saying he'd hit 52 sites in Iran if they hit us, which they clearly did, and he ripped Obama previously for drawing a red line and not enforcing it.

FAA has already issued no fly orders to US flagged carriers in the area. I suspect the area will be under full flight suspension by tomorrow. Reports of F-35 strike fighters departing al-Dhafra AFB in the UAE not too long ago. Could just be air cover, not necessarily strike missions.

1) Wouldn't 1-1 be 1|2? 2) What do you mean by 1-1-1-1? Is the dash meant to be a minus sign?

Not sure what you’re talking about here. My method isn’t a bastardised version; it’s how chemists draw structures when including lone pairs. It’s how Rachel (correctly) drew her structure in her first post. What I was saying was that drawing covalent bonds as electron dots is a bad habit (eg C::O instead of C=O). I didn’t say anything about lone pairs. Without the lone pairs it wouldn’t be a Lewis structure. Sorry if that wasn’t clear in my posts.

This is a perfect answer, but I doubt it would get any marks... What you're writing is educationally valuable but I think OTT for what should have been a simple question. Rachel: You seem to have to have reverse engineered the question and realised the author meant 'photon' rather than 'wave.' However you have unfortunately 'learned' that photon' and 'wave' are interchangeable, which needs to be unlearned ASAP. Wherever you learned about photons it was not from this question! I'll break the letter of 'Homework Help' rules and give you a (slightly) corrected answer. Saying in three different ways that frequency rises and wavelength falls, without repetition, is a challenge in itself... I think you need to mention photons if you go beyond "'Wave' in the question is a vague, undefined concept, and the effects of adding energy are therefor not predictable."

What a mess of a question. Well page 138 suggests we are talking about electromagnetic waves and the comment adjacent to Fig3 mentions swansont's other variable - amplitude. In the text it also refers to the relationship between frequency and wavelength I mentioned. Does the book say anywhere what the relationship between amplitude and energy is? (there is a very important one) After this you will know this substantially more than other less diligent students on your course.

Yes. Of course I could. And if I could not, I would openly acknowledge that and retract or alter my claim. Let me be clear though, are you asking me to name GOP congressmen who’ve regularly called for restricting presidential and federal powers powers in favor of state powers and smaller government... but who are now silent or even vocally supportive of Trumps executive overreach... or, are you asking me to name GOP congressmen who sought to limit what Obama could do militarily without congressional approval but who now vocally support Trump acting on his own? If it’s the latter (which is more thread relevant), then Mitch McConnell is the single most obvious example. You’ve maybe heard of others who’ve magically flip flopped on this issue like Orin Hatch and Marco Rubio or Jason Chaffetz, and there are scores of other congressional back benchers of whom you’ve likely never heard like Ted Poe of Texas who’s hypocrisy is on full display, too. There are more, and my position is NOT that democrats are never hypocrites (which would be absurd), but Raider made a pretty big claim there which quickly crumbled when it got even gently challenged. Regardless, I suspect this addresses the question more than suffiently and maybe now we can please return to the topic...

I am not entirely sure how "model organisms" is (meant to be) used here, but research in well understood model animals (flies, worms, mice etc) enables faster and more complex understanding because of how much we have already researched them. Model organisms have many (specific) uses, and understanding their limitations is obviously important. But let's look at the Seahare (Aplysia Californica); it has possibly one of the simplest learned/inducable reflexes that we can research, and the fundamental cellular machinery is in many ways quite close to that of humans (and in many ways far off, so its important to choose the right sort of model for the right type of question). By producing/breeding specific mutations into the Seahare and then observing the differences induced, we can see effects of genetic/genomic changes on "behaviour" (even if its a very simple reflex). This type of research gives us a lot of insight into what specific regions of the genome are responsible for. Additionally, a lot of the genome is much less understood and doesn't code for proteins, instead having regulatory functions. Highly controlled models will of course make it easier to find subtle differences that are the result of mutations in the non-protein parts of the DNA. Hope this is interesting information, even if it may not be exactly what you wanted to know. -Dagl

Any fool can make accusations. Everything accurately posted included reasons why it is known or is relevant. You constantly contradict Kirchoff's voltage law, Kirchoff's current law, Rosen's Theorem, Millman's Theorem, Node analysis, Loop analysis, Maxwell's mesh curent theorem, Norton's theorem, and Thevenin's theorem. Naysayers and extremists do that only to argue. You are clearly and repeatedly wrong. And anti-social to boot. Anything you say lacks credibility. First indication that you are lying are claims made without perspective - numbers. But once again, your bogus accusations have not one honest reason to justify it. Your only proof is in demaning others. An honest person would have said why those concepts were violated. You cannot. You simply demonstrate that any fool can post fancy terms to look intelligent. If you knew what those terms meant, then we read why each was relevant. That requires what you do not have - basic knowledge. The fundamental point remains unchallenged. Static electric discharges are an electric current between two charges. Earth ground is irrelevant. Only relevant are locations of those two charges. Sorry that is too complicated for an extremist naysayer to understand. But that is who you are. A conductor that connects those two charges ALWAYS has impedance. There is no perfect conductor as claims by the naysayers emotions. Electricity is defined by two relevant parameters - voltage and current. One is the independent variable. The other is a dependent variable. That relationship is defined by what always exists on conductors - impedance. If a conductor was perfects - as a nasty and ignorant naysayer claims, then no voltage can exist. Even students of high school science can understand that. A naive naysayer will post anything else just to waste bandwidth. Bugs Bunny best defines him. What a maroon.. Apparently a relevant difference between impedance and resistance was overlooked. That difference is significant even in superconductors. Furthermore zero resistance does not exist in a superconductor. A substantially lower resistance exists.

Do you switch on a current? Then it is not DC. That is taught in first semester course material. But somehow you know more? Clearly not. Because you do not know how to learn. That wikipedia quote is missing many relevant facts. And demonstrates how easily one can be scammed. One who is an expert but forgot to first learn. You are arguing and accusing when a responsible person instead would be learning and asking. You demonstrate why wacko extremists exist. Impedance is significant. Earliest radio transmitters simply turned on and off a DC current. Which creates currents at many frequencies. Static electric discharge is also not DC - for same reason. Lightning is simply a static electric discharge at higher energies. It causes radio frequency interference because "that flow of electrons in one direction" create radio frequency noise across all frequencies. Please learn these basic concepts before going off, half cocked, making claims only justified by a soundbite combined with junk science reasoning. First learn how electricity works. Quoting something subjective is the first indication that you are so easily scammed. You have no idea why impedance is significant. You did not even know that static discharges and its cousin, lightning, create AC currents. Only impedance (not resistance) is relevant. But that means becoming educated before lecturing anyone. Had you taken a first course in electrical theory, then you would have never posted such embarrassing ignorance. You simple demonstrate why extremism exists. Experts who did not bother to first learn reality.

Please do not be daft. Of course we measure the electricity. Some of the many parameters listed previously and repeatedly. Even your joule heating example says why electricity is not same at both ends of the wire. The fact that you ignore all three examples simply highlights that you do not understand those simple electrical concepts. But again, is the voltage same at both ends of a wire? Obviously not. Repeatedly stated. And constantly ignored by you. That is only one parameter. Plenty of other parameters also state quite clearly that electricity is different. Why do you constantly ignore the telegrapher's equation ... that also says electricity is different at both ends? What do you do with every example that demonstrates it? Ignore it. Please go back and learn this simple stuff before posting. It is not hard. Even voltage will be different at both ends. It is that simple. Stated repeatedly. And ignored. So even the car is different between 'here' and 'there'. You just said so. That analogy simply demonstrates what I have been saying all along.