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Janus

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Everything posted by Janus

  1. Again, F=ma merely gives a relationship between force, mass, and acceleration. It does not have anything to do with push or pull. It gives the magnitude of the force required, and isn't concerned as to the nature of, or how this force is provided. Here is another equation : F= mv2/r It tells you how much force is needed to constrain a mass to moving in a circle with a radius of r if it has a mass of m and has a speed of v. It makes no difference as to how that force is applied. It can be by a rope anchored at the center of the circle, a rocket engine mounted on the mass applying inward thrust, by the gravity of a central mass, or by the friction between a car's tires and the road.
  2. It is really important to grasp what the variables mean in each equation. In F=ma, we are talking about the amount of force needed to give a mass of m an acceleration of a With F = GMm/d^2 we are talking about the gravitational force acting between masses M and m at a center to center distance of d. To make this clearer, F is often written as Fg Now if we were considering how much acceleration mass m would undergo as the result of gravitational attraction between m and M, Then we we are saying that Fg is assuming the role of F in F=ma or that F=Fg thus we can substitute ma for Fg to get ma = GMm/d^2 cancel m on both sides of the equation and get a = GM/d^2, which tells us that the acceleration of m due to the gravitational attraction is independent of the magnitude of m's mass.
  3. As I already noted, 28,437 kph falls a bit below that for even a near surface orbit. To be lifted off "into space", using the Kármán line (at 100 km altitude) for the boundary of space, you would need to be moving at 28,498.5 kph. In which case, you would rise to a height of 100 km (the apogee of your orbit), and then drop back down to perigee at the surface, rise up to apogee... To leave the Earth's vicinity entirely, you'd need to be moving at 40,253 kph ( escape velocity)
  4. 1. It is meaningless to say "spin at 28,437 km", as rotation needs to be measured as angular velocity. (deg/hr, rad/sec. etc.) I know that it is common to express this in terms of tangential speed( in this case, at the equator) But it is sloppy and can lead to misunderstanding. For example if the Earth had a tangential speed of 28,437 kph at the equator, then at 45 north latitude it would only be 20,105 kph As swansont has pointed out there is a speed where the centripetal force (the force required to keep an object moving in circle) and the gravitational force balance out. This would result in the object going into orbit around the Earth. Gravity is still in play. In fact it is gravity that would prevent someone standing on the equator from just shooting out into space at in a straight line instead of just hovering over the Earth. And by the way, your number is a bit low, the equatorial speed would need to be 28463 kph And because of what I alluded to earlier, only someone on the equator would even go into orbit. People elsewhere will feel lighter, and the ground would seem to tilt a bit under their feet ( And even this is an over simplification which assumes the Earth maintains its present shape. If the Earth was indeed spinning this fast, its very shape would change, making it much more of an oblate spheroid.
  5. I wouldn't place too much faith in the polls; as of late, they have been shown to be highly unreliable. Right up to the '22 midterms they were predicting a "Red wave" with Republicans making large gains in the House (60+ seats). In the Ohio election dealing with the Republicans attempt to change the requirements to alter the state constitution, the polls said it was close and could go either way, while in the election it was overwhelmingly rejected. And most recently, a Democrat won in Florida in a red district when polls showed him losing. A lot of this can be put down to the polling methods not keeping up with the times and thus oversampling certain segments of the population and under-sampling others.
  6. While Trump will be sure to fill his administration with yes-men who's only qualifications are a sworn fealty to Trump. What little reining in and push-back he got last time will be nonexistent.
  7. That would only be applicable if you were shrinking the Earth in order to keep all of its mass contained within a sphere with a radius of r as r decreased. As you move towards the center of the Earth this is not the case, as the amount of material within r decreases as you do so and thus M is not a constant throughout the trip. So while at the surface of the Earth Gravitational potential is -GME/rE, at the center, it is -1.5GME/rE Thus the difference in gravitational potential between the surface of the Earth and its center is smaller than that between the surface and an infinite distance, and so would be the time dilation factor difference.
  8. The argument you so often hear is that gun regulations won't stop gun violence. It's the all or nothing approach; that if a regulation doesn't prevent all gun deaths of innocents, it shouldn't be enacted. Saving 10 lives a year isn't worth it, nor is saving 100 or, 1000...
  9. As pzkpfw alluded to, If it requires a new, now unknown, physics to allow for FTL, then it is pointless to speculate about what would happen, because we have no idea what rules we'd have to adhere to in this new physics.
  10. The Republicans have been playing this game with the border for years. They have no interest in dealing with it, as fixing it would give them one less thing to complain about, and all they have to run on are grievance issues.
  11. Agreed, the.. is a silly one. Good thing for the big bang model that it doesn't claim this.
  12. They didn't. The Babylonians divided the circle in 360 degrees. They then defined a "degree of time" as how long it took the Sun to travel 1 degree in the Sky, which they then divided into 60 minutes of 60 seconds each( we still see this in the practice of measuring angles in degree, minutes, seconds.) Thus the Babylonian minute and second were not the same duration as our modern one. The division of the day into hours was an invention of the Greeks. It wasn't until the middle ages that the two systems were combined, making the hour divisible in the same way that the Babylonian degree of time was. So, there is no mystery, as it is the result of cobbling together two different time keeping systems.
  13. It is not a contradiction, it just isn't compatible with the Newtonian model of time and space. And at its heart, Relativity uses a completely different model for these. In Relativity these measurements are not absolute but frame dependent. An analogy would be these images of two lines: The same set of lines, just viewed from different perspectives. In the first image the red line is "taller" than the green, and in the bottom image the green line is "taller" than the red. The point being that in Relativity, time and space are measured more like the "height" of the lines in the images and not by their absolute length.
  14. And considering that the magnitude of High-Low tide cycle coincides with the phases of the Moon, as does the varying time period between successive low and high tides (which can vary a fair amount to either side of 12hrs), It seems a bit silly to brush away the influence the Moon has on the tidal cycle.
  15. But, does the hen recognize what it has found, or is it just a shiny rock that attracts it attention? And for the hen's purposes, a nugget of gold is less valuable than a small rock. Chickens ingest these small rocks to hold in their gizzards, were they serve in lieu of teeth. The contractions of the gizzard use the rocks to grind up the grain, etc. into small digestible bits. Gold, being a soft metal, serves as a poor substitute for common rocks.
  16. You may "always hear that", but it isn't what model actually says. All it says is that the Universe, in it's earliest stages, was extremely hot and dense, and says nothing about it's size. One of the still unknowns about the universe is whether it is finite or infinite. The references to being "smaller than a proton" likely are referring with the "observable universe", which, for all we know, could be a tiny corner of a much vaster, or even infinite universe.
  17. That hasn't been my experience. Both my thumbnails look perfectly normal, and you'd never guess that anything out of the ordinary had ever happened to them.
  18. Unfortunately, it isn't the fungus that causes the regrowth. I talk from experience. Over my life I've lost two thumbnails, due to trauma, that then grew back.
  19. There is a neat story about Einstein concerning this. This occurred during some scientific conference. Einstein and a few others were at a table debating QM. Einstein would come up with some problem that he felt disputed QM, and the others would go over it until they found a flaw with his argument. Einstein finally came up with on that no one could find the flaw in. It started to get late, so they decided to call it a night. They met up again the next day. Whereupon Einstein stated that he'd been thinking about it, and had found the problem with his own argument.
  20. I fail to see where this would matter, other than Einstein taking credit for that which he was not due. It has nothing to do the validity of the conclusions. And as pointed in the previous post, the theory has survived every test thrown at it, and much of the equipment we use today would not function if it were incorrect to any large degree.
  21. Mine would most likely come through my paternal grandfather. But he was born nearly 170 years ago so it's a bit hard to verify.
  22. I came across some new info that solidifies the idea that I have at least some Sámi in my ancestry. It was a YouTube video which broke down the DNA of a Sámi male. It used results from the same test I took. It identified one of the genetic groups as matching one of mine. It returned a result of 7% Inuit, which adds weight to my suspicion of where my 2% result came from. The icing on the cake was in another video on the Sámi, which had a photo of a Sámi girl. I saw a strong resemblance to my sister. I called my wife over and asked her if the photo reminded her of anyone( without giving her any other context), and she said my sister. So while still not 100% conclusive, I'd say that the odds are pretty high.
  23. The issue I have with these polls is that I doubt that hey have changed their methods since the '22 primary. For example, they do phone polls. But these polls rely on people actually answering their phone. There is a generation gap in this factor. Younger people, who tend to vote more liberal, are much less likely, in general, to answer their phone when they get a call from an unrecognized number. Whereas people in the older age demographic, who tend to vote more conservative, in general, are more likely to do so. As a result, phone polls tend to over sample in favor of conservatives, even if they don't intend to.
  24. The galaxies that show blue shift are those that are part of our group or cluster. Galaxies are not evenly spread out but segregated into collections bound by gravity. First you have local groups of 50 or so galaxies, then these isolated groups form a cluster, then you get super clusters. Collections up to clusters are held together by mutual gravity and don't separate with the universal expansion. As a result, galaxies within them can have various velocities with respect to each other
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