Skyler4856

For Questions That Don't Merit Their Own Thread

1160 posts in this topic

On 2/11/2017 at 7:58 AM, Toonu said:

I'm not sure what is a negative mass or how in the predictions and concepts can someone make it. Is it somewhat connected to anti-matter mass? I m now talking about negative mass and Alcubierre warp drive. 

Thanks for reply! Ave! Toonu

Im not sure, and possibly nobody is sure, what properties "negative-mass" would have. However, I can tell you that anti-matter has positive (ie:normal) mass and behave exactly like regular matter in terms of gravity. Although it should be noted that only very small quantities of anti-matter have ever been experimented with (making measurements of the effects of gravity very difficult) and there are some schools of thought which posit that anti-matter may have different properties in a gravity field, or that it exerts a non-standard field itself, although the main-stream is currently that its mass is "normal" and wouldn't.

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So i poured some hot water into a cup and it started rotating. Then, on the side of the cup I observed a shadow on the side of the cup that had several, outstretched arms and looked like a galaxy. It was also rotating. Why was there a shadow when the water was rotating?

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On 23.12.2016 at 5:38 AM, shynung said:

What are the biggest hurdles in designing a working fusion power reactor today, in ELI5 terms?

Plasma cloud quickly (less than in a second) gets unstable and unhomogeneous.

To solve this problem they use such monstrosities (see the pictures and maybe links).

P.S.
Probably, the Rey's bread will be one more mysterious meal after the "The Good, the Bad and the Ugly" scene where they eat something (soup or something) unrecognized by the internet dwellers (I took a search once).

Spoiler

 

Also the bread color is like in Zardoz

Spoiler

zardoz-bread-oven.jpg

 

Edited by kerbiloid

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13 hours ago, munlander1 said:

Why was there a shadow when the water was rotating?

A change in the density of the water?  Refraction caused the light to be less?

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23 hours ago, munlander1 said:

So i poured some hot water into a cup and it started rotating. Then, on the side of the cup I observed a shadow on the side of the cup that had several, outstretched arms and looked like a galaxy. It was also rotating. Why was there a shadow when the water was rotating?

Rotating water generates all sorts of forces that distort the surface of the water away from perfect flatness. Curved surface of water acts as lens, concentrating light on parts of the inner mug surface, and directing light away from other parts, hence, "shadows".

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Why doesn't Space X use 1 big engine rather than 9 of the small Merlin engines on the Falcon 9?:/

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I'd guess many different reasons. I can think of two:

  1. Engines aren't made for a single rocket. The Falcon 1 uses the Merlin, too, and a single one. They could have made a bigger engine for the F9, or use 9 of the existing ones and spend their time upgrading it instead.
  2. During landing, it throttles its thrust down. However, that's not as easy engineering-wise as KSP will lead you to believe. It does so by firing in short (and FAST) bursts rather than full-on. Also, it lands on a single engine rather than all nine. That would be a lot harder to achieve with a single big engine.
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^ That. Also, developing a bigger, new engine would take up valuable time. 

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2 hours ago, Spyflare said:

Why doesn't Space X use 1 big engine rather than 9 of the small Merlin engines on the Falcon 9?

Because the Merlin was developed for Falcon 1.  When Falcon 1 failed to gain headway in the marketplace, there wasn't money or time to develop a new engine *and* a new booster before they were bankrupt.  Even so, it was a close run thing - the CRS contract arrived at the 11th hour.

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What is this effect called?  I've also seen it on t-shirts and such.  Really bugs out my eyes... yet I cannot look away!

3XPLAnR.jpg

 

I don't see it on Wikipedia's List of Optical Illusions, and googling the subject just comes up with clickbait articles.

 

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If Mar's (just an example) started orbiting earth, it would not longer be considered a planet. Correct?

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Ignoring practicality, launching from a high point like the summit of Everest would be better, because the rocket would already be nearly 9 kilometers up and launching in thinner air. Right?

Again, this is ignoring practical issues, like the transportation of rockets to such an obscenely high altitude.

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32 minutes ago, TheEpicSquared said:

Ignoring practicality, launching from a high point like the summit of Everest would be better, because the rocket would already be nearly 9 kilometers up and launching in thinner air. Right?

Moderately better, mostly because (as you surmise) your first stage engine(s) would not have to comprise *quite* so much on their nozzle designs.

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On 2/22/2017 at 4:00 PM, munlander1 said:

If Mar's (just an example) started orbiting earth, it would not longer be considered a planet. Correct?

Well... It might be considered a binary planet.

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7 minutes ago, Spaceception said:

Well... It might be considered a binary planet.

Probably not, IAU's definition has no provisions in it for binary planets. To be a planet, a body must orbit the Sun (so any body orbiting another body that is not the Sun cannot be a Planet, though there's another argument to be had about whether a Mars sized object orbiting the Earth might technically be orbiting the Sun in a binary system) but more importantly, it must have cleared it's orbital neighborhood (i.e be gravitationally dominant in it's neighbourhood), which may or may not be the case for this Earth-Mars system. 

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1 minute ago, Steel said:

Probably not, IAU's definition has no provisions in it for binary planets. To be a planet, a body must orbit the Sun (so any body orbiting another body that is not the Sun cannot be a Planet, though there's another argument to be had about whether a Mars sized object orbiting the Earth might technically be orbiting the Sun in a binary system) but more importantly, it must have cleared it's orbital neighborhood (i.e be gravitationally dominant in it's neighbourhood), which may or may not be the case for this Earth-Mars system. 

So, if for example we found a binary system with 2 objects larger than Earth, they would be considered dwarf planets before the IAU fixed planet definitions?

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19 minutes ago, Spaceception said:

So, if for example we found a binary system with 2 objects larger than Earth, they would be considered dwarf planets before the IAU fixed planet definitions?

To be honest I don't think that sort of system would be stable anyway, unless it was literally just a star being orbited by two planets in a binary system. I'm not sure they would be dwarf planets either because, depending on how you want to look at things, neither of them are technically orbiting the Sun.

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On 2/25/2017 at 3:30 PM, DerekL1963 said:

Moderately better, mostly because (as you surmise) your first stage engine(s) would not have to comprise *quite* so much on their nozzle designs.

The effect is more important with smaller rockets.  Pegasus gets a lot more cargo to orbit than you would expect for such a small rocket.  If I could pick a place to launch from without political considerations, I'd probably pick some place in Equador: not only high elevations, but near the equator.  Cotopaxi is ~19,000ft, and appears to have little settlement due West of it (less true for other mountains near Quito).  I have no idea if that mountain has any roads going to/near the top (I'm pretty sure at least one other does, but don't count on either good roads or well maintained buses.  And just because the locals can handle nearly 20,000 feet doesn't mean you can).

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4 hours ago, wumpus said:

Cotopaxi is ~19,000ft, and appears to have little settlement due West of it (less true for other mountains near Quito).

Which is of little interest - because you'll be dropping spent stages to the East.

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what is the easiest way to find center of pressure on a rocket?  *not in game* lol

to calculate it, i think im supposed to take the COP for all parts, then using the average distance for the sum from a specific reference frame. not 100 percent sure if thats correct, and not 100 percent sure how to calculate each piece to begin with.  

do we have a thread with info on this?

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5 minutes ago, DD_bwest said:

what is the easiest way to find center of pressure on a rocket?  *not in game* lol

to calculate it, i think im supposed to take the COP for all parts, then using the average distance for the sum from a specific reference frame. not 100 percent sure if thats correct, and not 100 percent sure how to calculate each piece to begin with.  

do we have a thread with info on this?

I know an easy way to do it for a model rocket. 

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