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That's a non sequitur. The NRA's opinion has no legal bearing because the NRA is not a part of the government. The Supreme Court is a part of the government. The Supreme Court's opinion is the supreme legal bearing in the US. Great Britain has a concept of parliamentary supremacy: The law is what Parliament says it is. The US rejects this notion, as do several other countries. Here, the courts can review the constitutionality of laws passed by legislative bodies. If the Supreme Court says that some law violates the constitution, that law essentially no longer exists. (Technical detail: Laws found to be unconstitutional remain on the books but they cannot be applied in any way.)

That's wikipedia for ya. Sometimes it's very good, other times, not good at all. This is one of those other times. Wikipedia has a perennial problem of giving undue voice to borderline topics. The concept of a "reactive centrifugal force" is one of those borderline topics that physics educators have been trying to eliminate for over a hundred years. There is no balancing force from the perspective of an inertial frame of reference. There can't be. The satellite is moving, and the motion is not along a straight line at a constant velocity. This means the net force cannot be zero. Surely not. Newton's cannon is an excellent way of looking at orbits. You should try to understand it.

The third law falls apart for fictitious forces. There is no third law counterpart to the centrifugal force, or to any other fictitious force. A real force, one that is subject to Newton's third law, is the same in all frames of reference. Fictitious forces on the other hand are frame-dependent. They're a fiction (a very convenient fiction) that results from force-fitting Newton's laws to a domain where they don't apply.

You feel pushed in toward the center, not away. Suppose you go around that corner a bit to fast, so fast that the door presses against you. The force that the door exerts on you is inward (centripetal), not outward (centrifugal). Now let's look at things from the perspective of a frame of reference fixed on you. From this perspective, you aren't moving. It's the road and the landscape that are moving from this perspective. Since you aren't moving the net force on you must be zero -- assuming Newton's laws of motion still apply. You can feel that force exerted by the door on you. That's a real force that can be measured. If Newton's laws still apply, that means there must be some other force you cannot feel that counteracts out this force that you can feel. This is the fictitious centrifugal force, and it's solely a result of assuming that Newton's laws still apply in this non-inertial frame of reference. Get rid of that assumption and you get rid of the centrifugal force. Fictitious forces such as the centrifugal force are a convenient fiction for extending Newton's first two laws of motion to a regime where they don't apply. One downside of this fiction is that you have to throw Newton's third law out. Newton's third law applies to real forces, but not to fictitious forces.

Start with a bad assumption, and you'll get a bad answer. Add in an overly simplistic model and you'll get an even worse answer. Young assumed that the current lunar recession rate is the lowest it's ever been. That's just wrong. There is a lot of history embedded in rock that tells how the length of a day has changed over the course of time. This in turn yields clues toward the rate at which the Moon has been receding from the Earth over time. The current rate is anomalistically high, about twice the average value for the past two billion years. Young's assumption of an ever decreasing recession rate was flat out wrong. Garbage in, garbage out. The reason the current recession rate is anomalistically high is the configuration of the continents. There are two huge north-south barriers to the tides, one from the southernmost tip of South America to the northernmost tip of Greenland, and the other from the southernmost tip of Africa to the northernmost tip of Siberia. That configuration is quite rare. At some times there was a more or less continuous path of ocean around the equator, which would have resulted in an anomalistically low recession rate. At other times, there has been one huge supercontinent, which would have presented but one barrier to the tides.

Which old book? I suggest a newer one such as Quaternions and Rotation Sequences: A Primer with Applications to Orbits, Aerospace and Virtual Reality by J. B. Kuipers. Chapter 11 discusses "quaternion calculus for kinematics and dynamics" (that's the title of the chapter).

Video @ vimeo

That's a zeroth order approximation, not a first order. To first order, there's an additional term that is proportional to the ratio of the Earth's radius to the distance between the Earth and the Moon. This is the tidal force. It's very small, on the order of 10-7 times the gravitational force exerted by the Earth, but it is very important. This tiny tidal force is what causes the tides. In addition to this direct way in which the Moon affects your weight (scale weight), here's also an indirect path. That tidal force does more than cause the ocean tides. It also causes the Earth itself to change shape. These Earth tides mean that you are pushed away from / pulled toward the center of the Earth as the Earth changes shape, and that too changes your scale weight by a tiny, tiny amount that is observable in the high precision gravimeters that Enthalpy referenced in post #5.

http://www.wolframalpha.com/input/?i=(gravitational+constant+*+moon+mass+/+(mean+earth-moon+distance)^2)+/++(standard+gravity) That's not really the answer you want, however, particularly since you referred to astronauts being "weightless" in your previous post. You are thinking of weight in terms of "scale weight" (aka "apparent weight", aka "proper weight") as opposed to "gravitational weight" (or just "weight" to some). You can't measure gravitational weight. You can measure scale weight. It's what your bathroom scale measures. So let's go to that previous post of yours: The difference is that the spacecraft is in free fall. An object at rest on the surface of the Earth obviously isn't in free fall. An accelerometer (a scale is essentially a one dimensional accelerometer) measures what is called "proper acceleration", acceleration with respect to a free-falling object. General relativity offers a very solid explanation why proper acceleration is so important, and why it is the best way to look at "weight". Scale weight is the product of proper acceleration and intrinsic mass.

Yes and no. It depends entirely on what you mean by weight. Legally, colloquially, and historically, weight is a synonym for mass. Ask someone how much they weigh and they'll give an answer in kilograms, stones, or pounds. Those are all units of mass, not force. (The pound is a unit of mass. The pound-force is a unit of force.) By this definition, yes, you're right, but you'll have to admit that this is a pretty lame justification for saying that you are correct. To scientists and engineers, weight is a force. One way of defining weight is as the gravitational force exerted by the Earth on the object in question. This definition of weight tautologically removes the influence of the Moon. So once again you are right by this definition. However, this is once again a rather lame justification for your point. So, let's extend that definition to the gravitational force exerted by everything in the universe. Per this definition, your weight does change based on the relative location of the Moon. The Moon makes you lightest when it is directly overhead, heaviest when it is directly underfoot. Not by much, a factor of ±3.4×10-6. Finally, let's use a definition of weight you can measure. (You can't measure gravitational force. You can only calculate it. Einstein's equivalence principle.) What you measure when you stand on a bathroom scale isn't the force of gravity. It's the sum of all forces *but* gravity. With this definition, the Moon makes you lightest when it is directly overhead or underfoot, heaviest when it is on the horizon. Now the variation is even less; tidal forces vary as 1/R3 rather than 1/R2. Either way, the right answer is "not by much". You said "not at all".

From the attached paper, Sigh. This is completely wrong. lidal, before you go any further down this path of trying to disprove physics, you need to learn some physics.

Well, yeah, his grammar is off. Then again, so is his understanding of physics. Elliptical orbits aren't understood? Seriously?

Actually, that's just about the only part of this paper that isn't nonsense. What he wrote there is spot on. There is a solid warning that nonsense is about to ensue prior to the bit you quoted. That warning: "Electrical engineer". I don't know why, but that field is a fast breeder reactor‎ for crackpots. The nonsense itself doesn't start until later on in the abstract, "Absolute motion can be detected by observing change of the law of gravitation in our reference frame." (No it can't.) This was followed by the utterly laughable "Despite the advance of physics, the cause for the elliptic shape of planetary orbits is unknown at a fundamental level todate (sic)." To lidal: Explaining the elliptical shape of planetary orbits is fundamental fare for a sophomore or junior physics major. It's a good idea to learn the very, very basics before starting commencing with tilting at windmills.

Nowhere. Everything in nature that is close to circular isn't quite a circle. That's irrelevant, however. While scientists and engineers use mathematics to describe reality, mathematics itself is not bound by reality. That a "pure circle" does not exist in physical reality doesn't matter to mathematicians. Even if a "pure circle" did exist in physical reality, it's circumference would not be exactly 2πr because physical reality is not Euclidean. Space-time is instead, as far as we know, pseudo-Riemannian. Rhetorical question: Did special and general relativity disprove Euclidean geometry? The answer is no. While those theories did show that Euclidean geometry isn't a perfect descriptor of our universe, they did not disprove Euclidean geometry itself. Mathematics is not bound by reality. That's nonsense. Jumping ahead to your next post where you expanded upon this, You are (a) spouting nonsense, (b) talking about the positive integers, and © assuming the positive integers are "perfect". I suggest that you read about Gödel's incompleteness theorems. Continuing with this next post, Yes, one or both of the radius and circumference must be irrational. The degree is defined as 1/360th of a full circle. You can't prove or disprove a definition.

Yep. The so-called WYSIWYG interface (what you see is what you get) is not WYSIWYG. Sometimes the formatting you see comes across in the post, sometimes it doesn't. Unfortunately, the so-called WYSIWYM interface (what you say is what you mean, which is supposedly what switching the toggle gives you) is not WYSIWYM. The principle author of this forum's software apparently is dead-set against markup or markdown languages. The software doesn't quite support this alternate editor, and sometimes it thinks knows better than you.

Pasting is going to try to preserve the font information from the source when you use the default WYSIWYG editor. It's a "feature". I typically don't want all that font embellishment; it's usually wrong in the context of a post. IMO, preserving font information is a misfeature, not a feature. The remedy is to get out of the WYSIWYG mode. (Another misfeature: WYSIWIG mode isn't quite WYSIWIG). When you are starting a new thread or replying to a post, you should see a command panel just below the topic title. At the far left there's a toggle switch icon. Click it. That will send you into bbedit mode. Pasting when you are in this mode pastes as plain text.

Bzzzt. Wrong. That is a doctored image. Look Ma: No streaks! Your video is complete nonsense, also. There is this thing called twilight, and it can last a long time in high latitudes. Civil twilight was over five hours long at Davis Station that day; nautical twilight, over eight hours long.

A small number of asteroids and short period comets have retrograde orbits. For an example of a comet that orbits retrograde, one need look no further than the most famous comet of all, Halley's Comet. The majority of long period comets apparently have a retrograde orbit.

Yes, it is. However, that does not necessarily mean that ionizing radiation is essential to creating a plasma. Heat will also do the trick.

No. You are conflating ionizing radiation with an ionized gas and are then extrapolating from there. There was very little, if any, ionizing radiation produced by the fireball. Ionizing radiation is x-rays and gamma rays, plus massive particles (i.e., not photons) moving at relativistic speeds. Even if the flash did produce some x-rays, gammas, or some very fast moving massive particles, that still doesn't mean that a thermonuclear reaction was involved. There was no such reaction. There was nothing to produce such a reaction, fusion or fission.

Nonsense. Richard Hoagland is an expert in two things, crackpottery and parting fools from their money.

Inverse tangent. You just need to take care to adjust the result for the fact that [imath]\arctan(y/x)[/imath] and [imath]\arctan(-y/-x)[/imath] yield the same answer. Many calculators and computers do this adjustment for you in a function typically called atan2. http://en.wikipedia.org/wiki/Atan2

Here's the original source for that 10 ton figure: http://www.ras.ru/news/shownews.aspx?id=1da2959b-902f-46b2-9f1f-0c62d19740e8 This might have been a preliminary estimate, or they might have intentionally downplayed the event. In any case, it's wrong. A ten ton meteor is not going to cause near as large a shock wave as the one that did occur, not is it going to register on seismic stations worldwide, or on nuclear test ban monitoring systems as far away as Australia.

That number (10 tons, metric or English, it doesn't matter) is just wrong. Meteoroids that small hit the Earth's atmosphere multiple times per year. They don't cause the kind of damage, let alone the brightness, that this one did.

You got that first number from wikipedia, which in turn got it from various British press sources, which in turn got it from ... where? The answer is that for the most part, they got it from each other. The news media don't do much independent journalism nowadays. One outlet might do a smattering of independent journalism, screwing up somewhere along the line. Then they'll sell that messed up story to other outlets.