## Search found 285 matches

Sat Jul 09, 2016 12:50 am UTC
Topic: 1702: "Home Itch Remedies"
Replies: 33
Views: 6919

### Re: 1702: "Home Itch Remedies"

Hehe ;) As a side note, the Icelandic language is unusually easy for making duck jokes because the word for "duck" and all of its various declensions (önd, andar, endur, andir, anda, öndum...) closely resembles a number of differents words used in forming compounds.(words equivalent to the...
Mon Jul 04, 2016 8:21 pm UTC
Topic: 1702: "Home Itch Remedies"
Replies: 33
Views: 6919

### Re: Home Itch Remedies

So the best home remedy is to move to Iceland Not a good idea... The name of the lake (Icelandic mý ("midge") and vatn ("lake"); the lake of midges) comes from the huge numbers of midges to be found there in the summer. Except that they don't bite. They form big clouds, and look...
Tue May 10, 2016 9:36 am UTC
Forum: Mathematics
Topic: Seemingly simple
Replies: 16
Views: 3904

### Re: Seemingly simple

C/x = B/sqrt(B^2 -(A-x)^2) This should be C/x = B/sqrt(B^2 + (A-x)^2), since sqrt(B^2 + (A-x)^2) is the length of the hypotenuse of the large right triangle. Then, C sqrt(B^2 + (A-x)^2) = B x C^2 (B^2 + (A-x)^2) = B^2 x^2 B^2 C^2 + A^2 C^2 - 2 A C^2 x + C^2 x^2 = B^2 x^2 0 = (B^2 - C^2) x^2 + (2 A ...
Tue May 10, 2016 7:49 am UTC
Forum: Mathematics
Topic: Seemingly simple
Replies: 16
Views: 3904

### Re: Seemingly simple

C/x = B/sqrt(B^2 -(A-x)^2) C = x * B/sqrt(B^2 -(A-x)^2) x * B/sqrt(B^2 -(A-x)^2) - C = 0 This isn't in the form Ax^2 + Bx + C = 0... and I don't remember how to get it in that form ;) And Wolfram Alpha last night was just looping forever, while today it says "Standard computing time exceeded&qu...
Tue May 10, 2016 12:49 am UTC
Forum: Mathematics
Topic: Seemingly simple
Replies: 16
Views: 3904

### Seemingly simple

Either I'm tired, an idiot, or this problem isn't as easy as it looks (solve for X; all corners that look like right angles are right angles):

Can anyone enlighten me as to which one it is?
Thu Mar 17, 2016 2:51 am UTC
Forum: What If?
Topic: What-If 0148: "Eat the Sun"
Replies: 40
Views: 29014

### Re: What-If 0148: "Eat the Sun"

Meh, Cadbury Creme Eggs are nothing. Here in Iceland we have "Páskaegg" (lit. "Easter Egg"), which are like this: Not purely a purely mid-Atlantic(-ridge) phenomenon, I assure you. I can't definitively speak for the US (I presume that it happens!) but the shops in the UK are ful...
Wed Mar 16, 2016 7:06 pm UTC
Forum: What If?
Topic: What-If 0148: "Eat the Sun"
Replies: 40
Views: 29014

### Re: What-If 0148: "Eat the Sun"

Now I just want to contribute to Randall's Creme Egg pile... Meh, Cadbury Creme Eggs are nothing. Here in Iceland we have "Páskaegg" (lit. "Easter Egg"), which are like this: https://c1.staticflickr.com/8/7615/17001375115_6e346a56d4.jpg http://www.visir.is/apps/pbcsi.dll/storyim...
Sat Feb 20, 2016 9:33 am UTC
Topic: 1645: "Toasts"
Replies: 81
Views: 19854

### Re: 1645: "Toasts"

Fri Feb 19, 2016 5:42 pm UTC
Topic: 1645: "Toasts"
Replies: 81
Views: 19854

### Re: 1645: "Toasts"

Okay, I guess my mind is in the gutter...

Fatheads for my real friends and real head for my fat friends.
Hotrods for my real friends and real rods for my hot friends.
Manholes for my real friends and a real holes for my man-friends.

... this is getting out of hand...
Sat Feb 13, 2016 5:39 pm UTC
Forum: Science
Topic: Venus chemical engineering
Replies: 0
Views: 3744

### Venus chemical engineering

Hi all. I've been idly thinking a lot about how to provision a floating colony on Venus in a simple, reliable manner. There are two issues I'm having a bit of trouble on: 1) Removal (to an exhaust stream) of SO2 from a stream also containing H2O and O2 2) Either: 2a) Separation of individual acids f...
Wed Feb 10, 2016 11:00 pm UTC
Forum: What If?
Topic: What-If 0145: "Fire From Moonlight"
Replies: 157
Views: 78900

### Re: What-If 0145: "Fire From Moonlight"

Simplest case: take a spherical black body at thermal equilibrium. Then put it next to a mirror. Not even a focusing mirror, just a simple plane. Doesn't the side of the black body facing the mirror end up warmer than the side facing away? This does assume the background is cooler than the black bo...
Wed Feb 10, 2016 10:31 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

This would require an infinitely large nozzle, so one does as much as they can with the nozzle that they have. The more gas involved (even gas that doesn't take part in the reaction), the more fully they can approach ambient for a given-sized nozzle. No, and actually the space shuttle main engines ...
Wed Feb 10, 2016 4:46 pm UTC
Forum: Science
Topic: Is the entire universe a black hole?
Replies: 13
Views: 4026

### Re: Is the entire universe a black hole?

Some interesting reading on the subject: http://cds.cern.ch/record/348993/files/9803052.pdf They posit an inflation-driven effect at high densities (a dilation gravity) that would mean that there's no such thing as a singularity, and that both black holes and our universe would be versions of the sa...
Wed Feb 10, 2016 2:30 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

Nope. Beyond a certain expansion ratio the vapour freezes solid. You can't expand solid material any further. Now you're back to the earlier, primary point: the advantages of having a working fluid (that's one of many). Nor is an infinite length nozzle optimal, because the nozzle weighs something. ...
Tue Feb 09, 2016 9:01 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

A rocket's efficiency is at a maximum when all of the heat of combustion and all of the pressure have been fully expanded to ambient temperature and pressure. No. That's a finite length nozzle, except in a perfect vacuum. And even there, there's a optimum nozzle length where increasing the length a...
Tue Feb 09, 2016 4:40 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

I think what some people are suggesting is essentially a scramjet/ramjet where the flame-holder is a rocket engine that provides the initial startup thrust to get it up to ramjet operational speeds then throttles back as the ramjet portion starts providing more thrust. Not exactly. The concept pres...
Tue Feb 09, 2016 4:21 pm UTC
Forum: Science
Topic: Wendelstein 7-X
Replies: 43
Views: 8667

### Re: Wendelstein 7-X

So, you have a variety of things carrying energy out of the reactor. Examples include: * The divertor (think "exhaust pipe") juts into the outer edges of plasma stream where it gets heavily bombarded by alpha particles (read: the helium it's trying to remove) * The first wall is subject to...
Thu Feb 04, 2016 2:05 pm UTC
Forum: Science
Topic: Wendelstein 7-X
Replies: 43
Views: 8667

### Re: Wendelstein 7-X

The magnets repel the plasma away from the vessel walls. Increasing the strength of the field increases the force of this repulsion, thus squeezing the plasma into a smaller space. I'm a little bit skeptical. What magnets repel the plasma away from the vessel wall? Magnets don't "repel plasma&...
Mon Feb 01, 2016 11:10 am UTC
Topic: 1637: "Salt Mine"
Replies: 57
Views: 12421

### Re: 1637: "Salt Mine"

mdog wrote:Hey, maybe protons only decay when they want to.

The electrons.... they're ANGRY!
Mon Feb 01, 2016 1:17 am UTC
Topic: 1633: "Possible Undiscovered Planets"
Replies: 104
Views: 17678

### Re: 1633: "Possible Undiscovered Planets"

How is continuing to snub Ceres a compromise? Ceres is the best! It's a cool little perfect (dwarf) planet, just barely big enough to be round on its own. Meh, Ceres isn't "just big enough to be round on its own". Vesta is a better description of that boundary, sort of a half-equilibrium ...
Sun Jan 31, 2016 2:19 am UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 35075

### Re: What-If 0143: "Europa Water Siphon"

I think the siphon in a vacuum question hinges on what the liquid does when the pressure drops to zero. Let's say there is an intermolecular force f between molecules in the liquid. Randall mentioned this in comment 5, and I and others have commented extensively on this above. It's as if the water ...
Sun Jan 31, 2016 2:12 am UTC
Forum: Science
Topic: Atomic Science books suggestion? For Layman and scientists
Replies: 11
Views: 3209

### Re: Atomic Science books suggestion? For Layman and scientis

I'm looking for more basic stuffs to build a foundation for more advanced knowledge. Your stuffs seem too advanced for me at the moment. Also, I'm interested in the history of the subject as well, so any suggestions satisfying that would be great. Thank you. What about this - is this too advanced? ...
Fri Jan 29, 2016 5:05 pm UTC
Forum: Language/Linguistics
Topic: most words with fewest different letters
Replies: 16
Views: 8710

### Re: most words with fewest different letters

There's also another problem that raises its head in that a child can't just read something simply because they know the letter. There's all sorts of rules and exceptions. If you want to work around this, you'll also have to add to your project a pronunciation list (IPA, for example), ideally includ...
Fri Jan 29, 2016 4:57 pm UTC
Forum: Language/Linguistics
Topic: most words with fewest different letters
Replies: 16
Views: 8710

### Re: most words with fewest different letters

Why do people use online services to solve problems like this? Don't you all have egrep/grep -E and /usr/share/dict/words? I'm curious, how would use egrep and a dictionary to solve this? I just can't see it. Well, there's not a "single" problem presented above. But since the main point i...
Fri Jan 29, 2016 1:46 pm UTC
Forum: Science
Topic: Atomic Science books suggestion? For Layman and scientists
Replies: 11
Views: 3209

### Re: Atomic Science books suggestion? For Layman and scientis

What's your current level of understanding of atomic physics? And what more specifically are you wanting to learn about? Basic summary: There are vast numbers of potential nuclear reactions when two or more particles interact at high (or sometimes, low) energies. For simple two body reactions, they'...
Fri Jan 29, 2016 1:55 am UTC
Forum: Science
Topic: Mixing things with different melting points
Replies: 6
Views: 4032

### Re: Mixing things with different melting points

The short answer is, it varies greatly depending on what you're mixing together. More to the point, some things won't truly mix at all, while others will form eutectics (mixtures). Even more to the point in your wax example, your wax *is* a mixture of different compounds (paraffins) with different m...
Fri Jan 29, 2016 1:42 am UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 35075

### Re: What-If 0143: "Europa Water Siphon"

Revisiting note #5, I think the video demonstrates that siphoning works just fine in a vacuum, and not "at least a little bit." We don't know the exact viscosity of the ionic liquid, but it seems to be siphoning at a reasonably quick pace, in the same ballpark (or at least the same county...
Thu Jan 28, 2016 4:45 pm UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 35075

### Re: What-If 0143: "Europa Water Siphon"

The reason stuff doesn't fall from Jupiter's orbit to Earth's orbit is because it's all in orbit around the sun. If a hose was stretched from Earth to Europa, I'm pretty sure it would actually end up functioning more like a space elevator, and anything that started to climb up the hose from Earth d...
Thu Jan 28, 2016 11:14 am UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

That's a really clever idea about using empty channels for injection of additional fuel or oxidizer in lieu of gimballing - I'm surprised that didn't occur to me, as I'm aware of the historic usage of propellant injection for thrust vectoring. I'll work that into the models and see how well it actua...
Thu Jan 28, 2016 10:21 am UTC
Forum: Science
Topic: Probable ninth planet?
Replies: 30
Views: 5173

### Re: Probable ninth planet?

It literally comes from the same root as "flow". That's not actually that compelling a piece of information by itself, given that "ball", "phallus", and "floral" also come from that same root. Except for, of course, the latter are related back in PIE (4th to ...
Thu Jan 28, 2016 10:14 am UTC
Forum: Language/Linguistics
Topic: most words with fewest different letters
Replies: 16
Views: 8710

### Re: most words with fewest different letters

Why do people use online services to solve problems like this? Don't you all have egrep/grep -E and /usr/share/dict/words? If everyone had those and knew how to use them, they presumably wouldn't come to forums with questions like this, so the fact that there's a thread about it makes the answer to...
Wed Jan 27, 2016 3:17 pm UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 35075

### Re: What-If 0143: "Europa Water Siphon"

There are siphons that operate under vacuum; the surface tension of the liquid can bind the two halves of the siphon together; the area labelled 'vacuum' opening up in the middle of the tube also represents more surface for the liquid. There's even a video demonstration of a siphon working under va...
Wed Jan 27, 2016 12:18 pm UTC
Forum: What If?
Topic: What-If 0143: "Europa Water Siphon"
Replies: 53
Views: 35075

### Re: What-If 0143: "Europa Water Siphon"

Very much disagree with this. An atmosphere isn't the only thing that can apply pressure. We know for a fact that sometimes there are geysers on Europa when the ocean breaks the surface. And that these geysers eject water upwards of at least 200km (possibly sometimes all the way to escape velocity),...
Wed Jan 27, 2016 1:51 am UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

The ideal SSTO-capable spacecraft could function as an induced-flow airbreather from standstill to transonic speeds, as a partially airbreathing ramrocket from transonic to hypersonic speeds, as a supersonic-flow air-augmented rocket from hypersonic speeds to ultrasonic speeds, and as a pure rocket...
Tue Jan 26, 2016 4:13 pm UTC
Forum: Language/Linguistics
Topic: to whistle-blow
Replies: 1
Views: 2914

### Re: to whistle-blow

Tue Jan 26, 2016 4:12 pm UTC
Forum: Language/Linguistics
Topic: back-formation. analogy
Replies: 1
Views: 2576

### Re: back-formation. analogy

That’s why I tried to form other verbs according to this model just using composition: 1. hand-finish, hand-assemble, hand-select and hand – choose. 2. to wife-hunt, to flat-hunt, to husband-hunt 3. to face-read, to smile read 4. to bread-fish, to dough-fish, to worm-fish 5. to heat-dry, to machine...
Mon Jan 25, 2016 11:27 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

The weight of the nozzle and the added ducting is unpleasant, but there haven't been many significant explorations of this concept as an integral design. I can't help but wonder if materials technology might deliver this one to us some day (suitable reductions in nozzle weight). For example, cerami...
Mon Jan 25, 2016 11:12 pm UTC
Forum: Science
Replies: 22
Views: 4236

### Re: What's up with avocados?

It's not super surprising that it lacks human-specific toxins while the dog-specific ones are still there. That's a myth according to google. The two avocado growers I know have to tie their dogs up as otherwise they eat so many avocados they become obese. Yep. But deadly poisonous to parrots. A nu...
Mon Jan 25, 2016 5:23 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

What do you mean by "ducts"? Do you mean an expanding nozzle? No, I mean a duct around the exterior of the engine that allows the exhaust to mix with an external airflow, reducing the effective exhaust velocity but increasing the mass flow without significant penalty. The thermal energy i...
Mon Jan 25, 2016 4:00 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13549

### Re: Landing rockets upright is unnecessary?

Partly on the topic of landing sideways.... I've occasionally given some thought to the use of ducted rockets as a means of altitude compensation and increased Isp. Adding ducts to existing rocket design costs more in weight penalty than it adds in efficiency, but this wouldn't be the case if you d...