Well, yeah, but I just used it as an example to say that it'd only happen if it were symmetrical to both axis.
sin (x + 1) would work, too.
[QUOTE=Turnips5;33708464]Yeah, I'm talking about waves-on-a-string type question here.
[editline]13th December 2011[/editline]
Basically, I need to draw a bunch of snapshot diagrams for two waves travelling in opposite directions. Is it an acceptable method to draw the two waves as if they were completely unaffected by each other (e.g. on separate strings), and then just add vector displacements?
It just seems weird to me that such waveforms can simply pass through each other like that.[/QUOTE]
Principle of superposition brah. That's how that shit works.
It is indeed. It's a familiar concept to me, I don't know why I'm finding it strange now.
Waves are just a bunch of particles pulling each other, so if there's two waves, there's two forces per particle. It makes sense that, if a force causes a particle to move x in an interval of time and the other causes it to move y in that same interval, that the net displacement would be x - y
[QUOTE=MountainWatcher;33709766]Waves are just a bunch of particles pulling each other[/QUOTE]
nyeeehhh depends on the wave
Well, yeah, I guess EM waves aren't like that because they aren't even about moving particles. The force of an Em field goes down with distance because of the whole field line density thing, right? And from simple trigonometry, less lines intersect a given area. So an EM wave is just about the position of those lines.
Out of all the science-docu's that have been about travel to other stars, they talk about using ships going at 50% the speed of light.
But they never mention time dilation. If they travel at 50% of the speed of light for 40 years, it'd feel like 40 years for the astronauts, but everyone on earth might even be dead when they have arrived to their location.
Is there really no way to travel fast and not be affected by time dilation this much?
[QUOTE=booster;33714875]Out of all the science-docu's that have been about travel to other stars, they talk about using ships going at 50% the speed of light.
But they never mention time dilation. If they travel at 50% of the speed of light for 40 years, it'd feel like 40 years for the astronauts, but everyone on earth might even be dead when they have arrived to their location.
Is there really no way to travel fast and not be affected by time dilation this much?[/QUOTE]
No need to worry about time dilation at 50% light speed because it's barely noticeable. The Lorentz factor at 0.5c is only about 1.15.
[QUOTE=sltungle;33714997]No need to worry about time dilation at 50% light speed because it's barely noticeable. The Lorentz factor at 0.5c is only about 1.15.[/QUOTE]
15% is hardly barely noticeable
Well this is great.
A thread just for me.
[QUOTE=JohnnyMo1;33720047]15% is hardly barely noticeable[/QUOTE]
When the worry is that people may be dead from old age after your 40 year journey then 15% really ISN'T that noticeable. It's only a 6 year difference in perceived time, not like... 3000 years.
I know the concept was canned in the Cold War era, but how feasible are nuclear powered aircraft? And if there is no feasible way to shield the crew from radiation (because lead is too heavy etc.), could it still be used for drones to stay in the air for weeks on end?
Long-distance space craft use plutonium 238 reactors, I believe. You could probably do something similar, but keep in mind you need more energy to keep a drone up than to just keep some radio going.
Its possible you could make a highly efficient reactor and have it connect directly to the propeller for less energy loss in the in-between stages.
If it was a drone used for spying you'd be better off without a reactor onboard, considering it adds weight, the threat of nuclear material being sprayed all over when it goes down, noise, and a [B]large[/B] heat signature.
Speaking of nuclear powered vehicles.
What safety meassures do ships/submarines powered by nuclear energy have if they sink to the bottom of the sea?
Would it be an enviromental hazard or is the nuclear fuel used so small it would barely have an impact?
[QUOTE=booster;33750124]Speaking of nuclear powered vehicles.
What safety meassures do ships/submarines powered by nuclear energy have if they sink to the bottom of the sea?
Would it be an enviromental hazard or is the nuclear fuel used so small it would barely have an impact?[/QUOTE]
very good containment - preventing anything from escaping into the sea.
[QUOTE=booster;33750124]Speaking of nuclear powered vehicles.
What safety meassures do ships/submarines powered by nuclear energy have if they sink to the bottom of the sea?
Would it be an enviromental hazard or is the nuclear fuel used so small it would barely have an impact?[/QUOTE]
As the post above said, containment.
But something that has to fly cant have a giant concrete/lead tomb around it.
Guys, just use mirrors to reflect the photons.
Is the power of a laser beam only "dependant" on how much energy the power source can create?
As in, can a laser beam contain an infinite ammount of energy?
[QUOTE=booster;33764022]Is the power of a laser beam only "dependant" on how much energy the power source can create?
As in, can a laser beam contain an infinite ammount of energy?[/QUOTE]
How can ANYTHING contain an infinite amount of energy if the energy of the universe is finite and constant?
Although, on the note of lasers, and the prior note of waves, what does white light look like if you draw it as a wave? Light of pure colours looks like regular sine waves, so does white light look like a superposition of blue, green and red?
[QUOTE=sltungle;33776979]How can ANYTHING contain an infinite amount of energy if the energy of the universe is finite and constant?[/QUOTE]
The point of his question, I think, was really asking if there is a limit to how much energy can be put into a single beam, or something.
[QUOTE=booster;33764022]Is the power of a laser beam only "dependant" on how much energy the power source can create?
As in, can a laser beam contain an infinite ammount of energy?[/QUOTE]
You need to be clear on what energy and power mean
Energy is the stored ability to make shit happen. Work done is how much energy was used (measured in the same units as energy). Power is the rate of energy transfer per unit time.
Work done = Power * Time
You can get incredibly high-power laser beams which fire for incredibly short times, so if you multiply a huge power by a tiny time, you'll get an energy that's somewhere in the middle (i.e. feasible).
I don't know how far you can go by having tinier firing times and larger laser power. There's almost certainly a limit but it's probably a technical thing.
15th anniversary of Carl Sagan's death :c
But it's Jaroslav Heyrovský's 121th birthday.
:v:
By the way, is there a proof for conservation of momentum?
[QUOTE=MountainWatcher;33829749]By the way, is there a proof for conservation of momentum?[/QUOTE]
Yeah, observation :v:
Yep
"proof" doesn't really exist in physics in the same way it does in math
Alright, I have a question. external product of vectors. Namely the external product of velocity and position in a circular motion which somehow gives out angular speed. Ho the hell does that work?
At school I'm on the debate team and this year we are debating if the us goggles should spend money on advancing the space exploration and or development. Its horrible to see 90% of the team strongly opposing it and calling it a huge waste of money on trying to leave earth. They laughed at SETI, Space platforms, asteroid mining, and a bunch of other plans. I feel there isn't enough teaching in schools aabout space, we should learn more about it rather than having a weeks lesson on it. I wish they were more educated as well as the country, on how beautiful and amazing space is and why we should take larger initiatives to expand from the earth into the stars, and not let our species eventually stagnate and die in the future.
Plus Carl Sagan is awesome
Sorry for grammar and spelling I'm on my phone
Well, honestly, I love space and all.
But it is very expensive with little-to-no benefit except for the sort of public motivation/happiness as was seen with the lunar landings, and our own habitat (the Earth) is already fucked up and needs some direction.
Maybe if we weren't ~15.1 trillion dollars in debt with a stunted economy I wouldn't mind spending 40 to 400 billion dollars on a temporary 6-10 person colonization of mars, but not right now.
[QUOTE=Collin665;33867174]Well, honestly, I love space and all.
But it is very expensive with little-to-no benefit except for the sort of public motivation/happiness as was seen with the lunar landings, and our own habitat (the Earth) is already fucked up and needs some direction.
Maybe if we weren't ~15.1 trillion dollars in debt with a stunted economy I wouldn't mind spending 40 to 400 billion dollars on a temporary 6-10 person colonization of mars, but not right now.[/QUOTE]
To quote something I said a few weeks back:
[quote]I've been thinking lately... the longer we put off venturing into the universe, the longer we take in seriously trying to establish an off-world presence... the more unlikely it gets that we ever will. We're dooming ourselves here.
Politicians keep putting these projects off because it's unpopular with the general public due to economic problems. Politicians would rather have 4, perhaps 8 years of guaranteed power than see the continued existence of the human race. We're told, "we'll do it next decade when we're not in debt!" but the longer we leave things, the more resources we as a species use, and the more resources we use the more expensive they become (due to their increased rarity). By putting off a serious space colonisation effort we're shunting it down the line to a time when we really DO need to leave Earth due to an impending disaster or a lack of resources to sustain us as a species - and when this time inevitably comes, when it finally becomes imperative that we leave Earth to survive as a species... it's going to be inobtainably expensive.
I only hope that when that time comes we as a species can cast aside the notion of money and wealth and work together as one to achieve a common, absolutely necessary goal.
... I only hope we can manage that.[/quote]
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