Just when you think you have it all figured out.

http://science.nasa.gov/headlines/y2...aug_solder.htm

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

Wow. A new Sci-Fi power source:

Engineer: Captain, the solar sail is damaged, warpdrive is out and impulse needs repair.
Captain: Then we'll have to use...
Engineer: Oh no. SRP?
Captain: Yes. Solder-Rosin Power.

Seriously though - to avoid weak solder connections in zero gravity they might have to invent a space-going soldering iron that wraps around the connection like pliers and vents the gas bubbles.

The smoke is rising...clearly faked. :wink:

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"That's Not Blight. It's New Jersey" - The Wall Street Journal

Gotta find out if anyone has video of a match being lit in zero-G. (or rather, the attempt)

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"Earth diameter is 7,900 miles, and Moon diameter is 2,160 miles. It takes on average 90 minutes to complete one Earth orbit, so one Moon orbit should take roughly 25 minutes." - Sam "NasaScam" Colby

Bearer of the highly coveted "I found Venus in nine Apollo photos" sweatsocks.

DataCable^2008 A+

isn't it a little obvious that the rosin ball is constantly being pushed to the otherside by the rising heat of the soldering iron? then it's inertia swings it around where it gets another push, getting faster because each time, it starts it's loop with an increased starting speed. It doesnt get pushed up because it is easier for the ball to just move to the left or right. the heat would have to be perfectly under it for it to be pushed up. The changes in direction are initiated by the movement of the soldering iron, which affect the angle of attack of the rising heat column.

This Doesn't happen in gravity because it has weight and is therfore pulled down with more than enough force to counteract any small force of rising heat over a weighted object.

It's like hosing a wheel. it gets faster and faster as it gets pushed by the water.

"Meanwhile, Grugel and his colleagues are brainstorming, trying to understand what causes the rosin to twirl. "We almost have it," Grugel says, but he's not ready to announce a solution yet"

I can't believe it isn't obvious to them.

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Faith: Not wanting to know what is true

Heat doesn't rise in microgravity. Rising heat is a manifestion of convection, which requires gravity. The heat from the soldering iron is being conducted along the metal wire, but it would conduct along it no matter what orientation the wire were in.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

the heat is rising from the soldering iron to the blob of solder, unless they are upside down, but then you get into what's up in space. Point was, the heat is pushing it, in it's travel direction from the source (soldering iron) to the blob

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Faith: Not wanting to know what is true

I understood this about air:

If something is hot, it weighs the same as if it were cold, but it just takes up more space.

This leads us to the concept of density. Because hat air takes up more space than cold air, hot air has a smaller density.

Less dense hot air will "float" above the more dense cold air.
therefore the heated air rose.

nothing to do with gravity.

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Faith: Not wanting to know what is true

Hot air floats because it is lighter than dense air, in gravity.

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þeodcyninga, þrym gefrunon,
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Actually, that's been done. Or candles anyways. they don't burn very well. Just a dim, blue ball of flame. Barely more than smolders.

NASA webpage

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Uhhh, that sounds a lot like perpetual motion, doesn't it?

If the heat from the iron is forcing the rosin to the far side of the solder ball, would it not also counter-act the rosin's momentum on the return trip? You're assuming that the propulsive force of the heat operates in only one rotational direction, whichever direction the rosin ball happens to be rotating, instead of a linear direction, through the center of the solder ball.

Put it another way: Assume a weight fixed on the end of a rotating arm. In the presence of gravity, the arm is rotated to nearly top-dead-center, and released. Would the arm swing all the way down to bottom-dead-center, continue rotating because of it's momentum all the way back up to top-dead-center, and start over again, moving faster, because of the combined force of momentum and gravity? Of course not. Once the weight passes bottom-dead-center, it would begin to decelerate, because gravity is now opposing it's momentum, rather than contributing to it.

Ok, in the absence (or nearly so) of gravity which way is "up?" Where is "under?" :wink:

Improper analogy. Directing a stream of water perpendicular against the surface of a wheel (rather than tangent to the surface) will cause no significant, sustained propulsive effect.

[edit: spelling, inproperly used "inertia" instead of "momentum" once]

__________________
"Earth diameter is 7,900 miles, and Moon diameter is 2,160 miles. It takes on average 90 minutes to complete one Earth orbit, so one Moon orbit should take roughly 25 minutes." - Sam "NasaScam" Colby

Bearer of the highly coveted "I found Venus in nine Apollo photos" sweatsocks.

DataCable^2008 A+

That'll teach me to post before Googling. :-# Whodathunkit, a whole website on candle flames in micro-G. =D>

Actually, I'm surprised they stay lit for any amount of time at all. As I understood it, the heat radiating from the source would force away the surrounding oxygen, snuffing the flame.

[edit: speeling]

__________________
"Earth diameter is 7,900 miles, and Moon diameter is 2,160 miles. It takes on average 90 minutes to complete one Earth orbit, so one Moon orbit should take roughly 25 minutes." - Sam "NasaScam" Colby

Bearer of the highly coveted "I found Venus in nine Apollo photos" sweatsocks.

DataCable^2008 A+

=D> no. perpetual motion is motion that is sustained by it's own motion.

no. think about it. on it's return trip it has enough momentum to push through that force itself.
I didn't think the propulsive force of the heat operates in a rotational direction at all.

er... I dont know what the point was here...

up is the direction from the bottom of the frame to the top as viewed by the camera. it is a PERCEIVED up. You missed the point in your desire to come out looking like a real cool smart person here. We all know that there's no true up or down in space. only a perceived one which is relative to the viewer. it isn't clever to point that out so your use of a wink is a little moot

Again you didn't think about it enough. I didn't say perpendicular, that was your word. Naturally, it would need to be at a slight angle. (I can't believe I am having to explain this to you) Also, in no gravity, it would have an increased effect. (in the same way that your weightlessness would have an increased effect back to normal zero weight when outside the pull of gravity) However little it may be, the eventual cause would be rotation. Of course there is an optimum angle for the fastest accelleration, but any angle will get the thing moving.

You seem to read into things too much, and end up adding imaginary data. Try not to do that please, especially with my posts.
Besides, I have abandoned that theory now, I have seen other flaws in it so there is no point discussing it further.

But I would like to hear some other peoples ideas on why it might be happening. Unless everyone is afraid of proposing silly ideas because of the attitude of DataCable. I for one would like to hear ideas on this from people, no matter how silly they seem. And I for one won't make myself look like a know-it-all and try to make myself look smarter than you in a smuggish way....
(I wonder why these type of boards bring out that in people)

In the proposing of silly ideas and putting them up for discusion, things can be learned. Einstein knew this. Using the post feature for self ego stroking is counter productive.

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Faith: Not wanting to know what is true

It has certainly brought it out in you. I suggest you tame the attitude down somewhat and perhaps stop slinging insults at people?

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þeodcyninga, þrym gefrunon,
hu ða æþelingas ellen fremedon.

I didn't insult anyone...

what was my insult. DO NOT accuse me of stuff I didnt do.

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Faith: Not wanting to know what is true

Let's calm down, folks. It's not about who knows more than whom. For my purposes, my comment was not intended to make anyone feel bad.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

That implies that someone (perhaps dataCable since you mentioned him earlier in the paragraph) is doing that. I guess I was wrong though. Sorry.

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þeodcyninga, þrym gefrunon,
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Fluids behave slightly differently than solids. Gases behave slightly different than liquids. These differences are due to the nature of their state.

Your first statement for gases is a little difficult, because gases do not have a set size, they expand to fill whatever volume is available*. Thus to speak of gases requires speaking of pressure and volume as much as mass. You can define a certain mass of gas, but is that mass contained in a small vessel at high pressure or in a large vessel at low pressure? That creates density changes without temperature changes. Also, stick the gas in a rigid container, heat it up. The gas does not take up more space, it raises pressure.

Okay, we're talking about in an atmosphere. Assume some imaginary control mass of atmosphere at local conditions (i.e. standard temp and pressure). By heating that mass (and assuming standard conditions means the mass is allowed to expand uncontrolled*), the air expands. Then yes, we get a density change due to temperature increase.

* The atmosphere seems to expand forever from our perspective, but really that is not quite true. Gravity provides a force that counters the expansion of the gas, holding the atmosphere to the planet. So the gas will expand because there is no solid container of, say, metal constraining it, but it is constrained by its weight - i.e. the pull of gravity.

Incorrect, it has everything to do with gravity. Without gravity, there is no driving force to move the hot air or cold air. Less dense objects rise over more dense objects because gravity pulls the more dense objects downward. Just like a weight in a container of water - in zero-g, the weight floats in the middle of the tank because there's no force to pull it to any side. The cold air is your weight and the hot air the water - without gravity to pull the weight to one side or the other, the air just slowly mixes and reaches equilibrium.

[quote="DataCable"]If the heat from the iron is forcing the rosin to the far side of the solder ball, would it not also counter-act the rosin's momentum on the return trip? You're assuming that the propulsive force of the heat operates in only one rotational direction, whichever direction the rosin ball happens to be rotating, instead of a linear direction, through the center of the solder ball.

How does the rosin ball gain enough momentum from the first push to counteract that same push as it returns? That is the point of DataCable's description of a weight on a rotating arm in gravity. The pull of gravity accelerates the weight downward, just like your description of the heat pushing the rosin glob away. The rigid arm serves the same function as the surface tension forces holding the glob of rosin to the solder. In a gravity field, the weight gets pulled all the way to the bottom but then on the upward swing the same magnitude of gravity pulls against the climb, slowing the weight to the top, not speeding it up so it goes around faster. For the rosin