ParadigmShifter
Random Nonsense Generator
Never wash your clothes in supercritical water. "That jumper makes you look fat", "those jeans went out of fashion years ago!" etc.
Science questions not worth a thread I: I'm a moron!
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PlutonianEmpire
King of the Plutonian Empire
I remember a few weeks ago, there were some articles about some tidal forces being strong enough to strip planets and and moons of their water after causing runaway greenhouses. I recall one of them stating that when Earth's moon first formed, Earth had a brief period of runaway greenhouse due to the tidal forces from the moon, which after about a dozen million years, ended because the moon got far enough away that the tidal forces weren't strong enough to eliminate Earth's oceans.
At what distance from Earth might the moon have been when the tidal forces got low enough for the oceans to survive, assuming the articles are correct?
At what distance from Earth might the moon have been when the tidal forces got low enough for the oceans to survive, assuming the articles are correct?
Bluemofia
F=ma
A bucket of water at the triple point will be ice with water with steam. Of course, the steam is colorless, but still.
Basically, it will look similar to ice cubes sitting in a drink on the smallest of scales, you know how the ice sort of sticks together and actually forms ice between them? The ice is spontaneously forming and being broken down, but with a slight imbalance towards breaking down.
The triple point will be the same thing, but with liquid to gas as well as the solid to liquid, but without an imbalance. At any given time you will have the same amount of gas, liquid, or solid as any other given time. But the molecules could be in any of those states.
The bucket of super-critical water should look like normal water. Though if you disturb it slightly, such as dropping a few grains of salt into it, or bumping the glass, it will suddenly boil over, concentrating on the crystals or the point of impact. This tends to make it violently boil pretty much from every depth of the bucket at once, and it is not fun to be close to it. (From personal experience when trying to rush boiling a beaker of water in AP Chemistry when a lab was running late)
Er, that's superheated water. Supercritical water is when liquid and gas are the same thing.
Bluemofia
F=ma
Yeah, you're right. My mistake.
PlutonianEmpire
King of the Plutonian Empire
A friend asked me a common question: How much does Jupiter weigh?
I can't remember the details of the answer to that question, but how do I explain it as close to laymans terms as possible?
I can't remember the details of the answer to that question, but how do I explain it as close to laymans terms as possible?
Mass and weight are different things. On Earth you can use them interchangeably but elsewhere they're discrete units of measure. Mass is how much matter something contains (bit more technical than that, but for layman's definitions...) whereas weight is how two objects of mass interact with one another. If you weigh 100kg on Earth, you would weigh a little under 17kg on the moon, assuming you stayed the same mass.
Jupiter is 318ish Earth masses, or something like 1.9x10^27kg.
madviking
north american scum
damn avatar switch messin' me up
Mise
isle of lucy
Yeah, holy hell 
If you are 100kg on earth, you're still 100kg on the moon, since kg is a measure of mass, not weight.
Pop Quiz:
I'm right now holding something that weighs more on the moon than it does here.
How can that be, knowing that moon's gravity is ~1/6 that of Earth....?
What am I holding?
I'm right now holding something that weighs more on the moon than it does here.
How can that be, knowing that moon's gravity is ~1/6 that of Earth....?
What am I holding?
If you are 100kg on earth, you're still 100kg on the moon, since kg is a measure of mass, not weight.
When people say they weigh X Newtons, I'll no longer want to slap you.
I'm guessing a buoyant gas.
IdiotsOpposite
Boom, headshot.
A bag full of negatrons!
Negatron - made-up word meaning something with negative mass.
contre said:
Yup. Helium balloon. Stolen from the Car Talk puzzler - fastest one I ever solved.
ParadigmShifter
Random Nonsense Generator
I think a helium balloon would weigh less on the moon as well. Weight is mass times gravity. Mass is the same, gravity is less too.
IdiotsOpposite
Boom, headshot.
I guess it depends on whether you factor air resistance into weight.
ParadigmShifter
Random Nonsense Generator
Air resistance affects velocity, not weight. N00b
PlutonianEmpire
King of the Plutonian Empire
Would a smartphone, such as the latest android or iphone, theoretically work in the vacuum of space (granted the sound from the speakers would have nothing to propagate through) by itself, or does it require an atmosphere in order to work, or at least some sort of protection?
Mostly it should work, at least for a while. There are some things that won't work at all: As you said the speakers won't work and as the oscillation of the membrane is not damped by air anymore, trying to use them might break them easily. Then the acceleration sensors will not work as intended, because the phone cannot determine its orientation by measuring gravity. This might mess with the user interface or some controls. Last, you are not going to get any signal unless you place a relay nearby.
I don't see any other function that would not work at all, but there will be issues limiting the lifetime of the phone. The first one is heat. Usually the phone is cooled by convection in air, which won't work in a vacuum. If no alternate means of cooling is provided, the phone might overheat quickly. So you would need to cool it somehow.
Then there is radiation. If the electronics are not radiation hardened (and I don't see why the designers should have cared for that) and they are placed outside the van Allen belt they will fail sooner or later due to degradation by radiation. If the phone is supposed to be operated by humans, they will also suffer the radiation, so it would be in their interest to minimize radiation, anyway.
The limiting factor will be outgassing. All materials will slowly evaporate when placed in a vacuum. For most metals this will be very slow, but some polymers have a high outgassing rate. If the rate is too high, the material will evaporate until there is nothing left anymore. And if this material had a critical function, the phone will fail when it's gone. How long this would take depends on the materials used and their function.
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