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Showing content with the highest reputation on 01/20/23 in all areas

  1. https://www.bbc.co.uk/news/av/world-europe-64352634 Interesting observation of UFO shaped clouds
    1 point
  2. No, the galaxies are not moving away from us through space at that speed. The galaxies are not moving through space at that speed relative to us so the KE equation you presented does not apply.
    1 point
  3. One can get many inconsistencies if one mixes freely these two different models. To be consistent, one should not generally do it, although it works sometimes if applied very carefully and in a restricted domain. In particular, if you use Newtonian perspective, then there is no speed limit. And if use GR, then the galaxies do not move faster than light. Each picture is consistent within itself.
    1 point
  4. Those are not “kinds” of KE. KEi and KEf are the kinetic energy at two points in time. What about it? There are several equations one might use to determine the KE, depending on the details of the problem. But there will still be a KE at the beginning if the problem, and one at the end. No, I didn’t mean that, nor did I say that. Every object can have a value for KE. If the object is at rest, it has zero KE. v=0, and KE = 1/2 mv^2
    1 point
  5. In putting together maintenance teams, it's common practise to pair up a 'bright spark' with a 'steady Eddie'. One to determine the root cause of the problem, and one to see that it's properly dealt with. Their strength is in their diversity, and I strongly believe similar priciples are true on a broader scale in society as a whole. But above all, I have a profound distrust of those who promote IQ testing, for reasons best summed up in https://en.wikipedia.org/wiki/Buck_v._Bell. (It's still on the statute books).
    1 point
  6. My guess is that the referred article was written by the same till operator that gave me the wrong change this afternoon.
    1 point
  7. n is proportional to q. This means that making q twice as big makes n twice as big. n is proportional to r. This means that making r 3 times as big makes n 3 times as big. Now, what happens to n if q is made twice as big and r is made 3 times as big? n should become 6 times as big. I.e., n is proportional to q*r. For example, in my last derivation on step 1, F(r) is some function of r. It depends on r, but it does not depend on q, i.e., it is independent of q. "F depends on r" means that if r varies, F might vary. "F does not depend on q, i.e., it is independent of q" means that varying q alone does not have any effect on F.
    1 point
  8. Also, most fish, I think, have many bones and/or cartilage protecting all organs. These don't cost much in the water as long as they are attached flexibly.
    1 point
  9. When you have long legs and lots of clearance, your belly doesn't need as much protection as when you crawl on or close to the ground.
    1 point
  10. It did. They were called gastralia and are seen commonly enough across the lineages that led to both mammals and reptiles for us to be pretty sure that our own ancestors probably had them oto 300 miilion years ago. And slowly over time, all lineages lost them except for the tuatara and crocodilians in the present day. And the only reason we lost them is that the return didn't repay the investment as well as alternative developments did.
    1 point
  11. Misner/Thorne/Wheeler “Gravitation” describes this in some detail. Consider first the general form of the FLRW metric: \[ds^{2} =-dt^{2} +a( t)^{2} d\Sigma ^{2}\] wherein \(\Sigma\) designates a 3-surface of uniform curvature (which could thus be elliptical, Euclidean or hyperbolic). The full Riemann tensor for 3D+1 spacetime with this type of metric then has six functionally independent components: \[R_{1100} =R_{2200} =R_{3300} =a\ddot{a}\] \[R_{1122} =R_{2233} =R_{3311} =-a^{2}\dot{a}^{2}\] Thus spacetime is never Riemann-flat, unless a(t)=const. On the other hand, the 3D+0 Riemann tensor for a given 3-surface \(d\Sigma\) of space is \[^{3}R_{ijkl} =\frac{k}{a( t)^{2}}( g_{ik} g_{il} -g_{il} g_{jk})\] wherein k is called the curvature parameter, so that for the choice k=0 each 3-surface is Euclidean and flat. MTW motivates the presence of the curvature parameter in this expression by using the following exact solution of the field equations: \[d\tau ^{2} =-dt^{2} +a( t)^{2}\left(\frac{du^{2}}{1-ku^{2}} +u^{2} d\phi ^{2}\right) ;\ u=\frac{r}{a( t)}\] wherein t is the total time recorded on a co-moving “dust clock” since the beginning of the universe.
    1 point
  12. Reported for spamming No it isn't. Pi is normally represented by the lower case π rather than the upper case form Π. In fact, I have never seen the latter used. But you seem to be basing this idea on a superficial similarity in form between the Hebrew letter Heth and (upper case Pi). But what about He or Taw? They also resemble Pi. And, obviously, the letter Heth (and He and Taw) appears throughout the bIble not just in this chapter and verse. So, like all numerologists, you have noticed one approximate and inaccurate and assumed it has far greater significance than it does. Could you also explain how the authors of the Old Testament text knew that in 1700 (ish) someone would decide to use the (lower case) Pi as a shorthand for a number? I think we will be the judge of that. (AndI am fairly certain the answer would be: "oh no it doesn't; it just more ludicrous".) But thanks for posting the stupidest thread I have seen for a while. Quite amusing.
    1 point
  13. Note the words "entire sequence of the pi number." This demonstrates the statement is false, since the Bible is finite and the number of digits in pi is not.
    1 point
  14. is called "frequency" f=(theta/t)*(1 [cycle]/360°) =1/T for the angle theta in (units) [degree(s)]=[°]; t is an amount of time (duration, e.g. difference in time) in (units) [second(s)]; & period T is the (amount of) time (duration), per cycle. There are several ways to express angle & (thus, also) angle_speed. But I prefer to express angles in cycles(' fractions, &/or multiples), e.g. as fractions, &/or multiples of a cycle. 1=100%. E.g. 1 [cycle]=360°. That is(=means), a degree 1°=[cycle]*(1/360) is 1/360th part of a(=1, complete=whole, single) cycle. E.g. 90°=0.25*[cycle]=[cycle]/4. 1 [cycle]=(t/T)*(360°/theta), or (rearranged) 1 [cycle]=(t/theta)*(360°/T). Or regrouping the angles together as a ratio f=(theta/360°)*(1 [cycle]/t) =1/T. A few other variations for the angle_per_time ratio, are theta/t=(360°/T)*(1/(1 [cycle])), or swapping (Rt side) denominators theta/t=(360°/(1 [cycle]))*(1/T), is also theta/t=(360°/(T*[cycle])), 1/T=f theta/t=f*360°/[cycle]. The period, is T=t/(1 [cycle]))*(360°/theta), or T=(t/theta)*(360°/(1 [cycle])). The angle (in degrees), is theta=(t/(1 [cycle]))*(360°/T), or theta=(360°/(1 [cycle]))*(t/T). The angle (in cycles), is f*[seconds]. (Even) although I'( a)m in the habit of using degrees. I hope that clears any confusion. Motivation: I noticed a general formula for angle_speed was a little bit more involved, & (so) I was searching for an appropriate syntax (symbol, hieroglyphics). I hope that will (simply) do with an (already) existing symbol f. ?
    -2 points
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