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Everything posted by oxy126

  1. The second-largest moon in our solar system, Titan, orbits around Saturn, about 8.5 AU (the distance from Earth to the Sun) away from us, making it a very chilly place. A fairly massive moon (80% more massive than our moon, according to Wikipedia), it has the unique characteristic of having an atmosphere that obscured views of the surface until the launch of the Cassini-Huygens mission in 2004, designed to chart out primarily the Saturn system. A moon with an atmosphere is strange, and interesting. But what makes Titan truly intriguing is the presence of a liquid cycle, akin to our water cycle, in it's atmosphere and on it's surface. An average temperature of -179.5 degrees Celsius means that this liquid isn't water - it's methane. The atmosphere and oceans of Titan are composed of liquid methane, which, under the conditions on the surface, acts similarly to water. It evaporates, precipitates, and forms liquid bodies and oceans, just like on Earth. Deeper down below the surface, there is, in fact, liquid water too, at higher temperatures and pressures beneath an icy "crust". Titan is a strange planet, but interesting in it's composition. With a thicker, denser, and "taller" atmosphere than our own, it has some unique properties, and manages to be Earth-like in strange ways, by substituting life-giving water with a whole lot of poisonous (to us) hydrocarbons. But it is interesting nonetheless.
  2. oxy126

    Ice Ice Baby

    There would be much less ice skating and the Titanic wouldn't of sunk... and snow might be quite weird, if it still existed. The oceans might have some interesting convection patterns and the Antarctic would probably be much different. While I don't know for sure, it's an interesting thing to ponder.
  3. oxy126

    Ice Ice Baby

    Water is strange. Unlike most compounds, its solid form is (normally) less dense, and of a larger volume than its liquid form. Because of this, its very difficult to compress water, because normally there isn't really anything to compress it into. But the story of ice is a bit different from the snow and hail we see falling outside of our windows during these winter months. In fact, ice has many different forms, depending on the conditions it forms in. The ice we commonly know is called Ih - a common ice type with a hexagonal structure. But as you can see from the picture, there are many different types of ice. Ic is also a (relatively speaking) common ice type, with a cubic structure that can be present in the upper atmosphere. In total there are 15 different types of ice, all forming at different pressures and temperatures, all with different crystal structures, densities, and electrical properties. For example, while water is hard to compress, when put under great enough pressure at normal temperatures, can form into ice IV (not pictured), a denser form of ice. While most variations are just density and structure based, certain forms (like ice XI) have ferroelectric properties, which is something I looked up and failed to understand, but it sounded interesting. And noticing the lower pressures, below ~1 kPa (about 1/100 of normal sea pressure), liquid water fails to exist, and water vapour will undergo deposition straight into ice below this point. As we head into winter, it's interesting to note the complexities of such a common substance. It can take on many forms with many properties, and I think that's pretty cool.
  4. I'm a big fan of sound. Music for me is a nice blend of science and art, and I take strides to better my understanding of it occasionally. And occasionally, I enjoy listening to chiptune songs - 8-bit music, as you may call it. A typical sound wave is sinusoidal, meaning it looks like a sine/cosine curve. This is the natural state of a pressure fluctuation that is sound. However, sound waves are (obviously) not all sine waves. Because of the constructive/destructive interference of waves, waves with a new shape - or timbre - like with a square or saw wave, essentially keeping the dominant frequency (pitch) of the note while still changing how it sounds. What is really happening when this is going on is that, in some ways, the frequency is changing, but just not the dominant frequency. In music, an octave occurs when one note has double the frequency of another, and by changing the amount of sound energy contained in a certain frequency that is an integer multiple of the base frequency (be it an octave or a different multiple), you can change the timbre without distorting pitch. This is the fundemental basis lying behind the Fourier transform, a method for breaking down a period function into an (often infinite) sum of sine waves with different frequencies. With bar-based music visualizers, the same things is happening, with wave shapes being analyzed for the frequencies they contain. But this phenomenom is what makes music sound the way it does, and it demonstrates that wave interference can have some interesting and melodic effects.
  5. I hope so... that would be pretty sweet.
  6. A lot of games let you fly planes, but when was the last time one let you fly a rocket? While if that has been what you've been looking for in your time-wasting pursuits, wait no longer, for Kerbal Space Program lets you do just that. As the director/god of the aptly named Kerbal Space Program, you have the ability to launch probes, satellites, landers, space planes, and a whole plethora of fancy little stuff. But behind all of this glamour comes (simplified) rocket science. Much like real rocket scientists, you have to design a craft with fuel and power constraints in mind. Going to the Mun may not be as trivial a task as some may hope. If you prefer fast paced action, this game probably isn't for you. But if you're willing to think a bit, ponder questions about choosing an engine with a larger thrust to weight ratio versus one with a higher specific impulse, or how you should stage your creation to successfully land on Minmus and return home safely, this might just be your cup of tea. I recommend checking it out.
  7. Boomerangs to some can be quite mysterious. One may ask, "why do they fly the way they do?" But fear not, for I'm here to explain them to you. At first glance, a boomerang might appear flat to the unsuspecting eye. But alas, for a boomerang to return to your hand, it must actually act a bit like a helicopter rotor, with one side angled up one way and the other the other way, so that when it spins it creates lift. But when you think of a helicopter, you think of something going up and down, not around in a circle. What you don't consider is that lateral movement of the boomerang cause air to flow past one side of the boomerang faster than the other as it rotates, create unequal lift, causing it to turn (this means two things: one, boomerangs are thrown vertically/almost vertically as opposed to horizontally, because that would cause more of a loop-de-loop, and it also displays one of the major shortcomings of single-rotor helicopters: they suffer from this same issue). It continues to turn as it flies, eventually creating the loop we all know and love. So if you're making a boomerang, keep this in mind: angle the fins. And for legal purposes I do not support the use of boomerangs as a projectile weapon. Thank you and goodnight.
  8. The trebuchet is an old art. Last time it was seriously used, people were assaulting castles and pillaging the countryside (for the most part). But oddly enough, for a time period associated with such little scientific innovation, is the trebuchet really so complex? It isn't hard to think why it works: it pulls a sling, that sling releases, and so away it flies. But for accurate predictions and optimization, it is actually a fairly complex beast. You may expect me to explain how it works. Well, I won't. It's complex enough where few definitive outlines exist for their ideal mathematical operations, and presently I don't have the time to take a crack at all that math. But I mention it because I feel as though it is a good example of complexity generated not by subject matter but rather the amount of subject involved. You have the sling, rotating around the end of the lever arm. You have the counterweight and beam, a first class lever, and in the real world, that beam has a linear mass density as well. You have friction around the fulcrum, friction in the chute, and a need for precise timing with the release of the ring from the end of the payload side of the beam (NOTE: if none of this makes sense to you, I would advise checking out http://www.redstoneprojects.com/trebuchetstore/how_a_trebuchet_catapult_works.html - it gives you a basic overview of how it all works). While this is all stuff we've covered, concepts we know, the fact that they are all combined in a complex system makes it much more difficult to be precise with. So just take note that, while solving problems using these concepts may seem easy, similar problems can become much harder with just a few things added in. Me, personally, I like this. It means there are always new things to try and explore.
  9. I thank you for your informative post and drawing. I'll make sure to pursue less combustible options of leaving Earth from now on.
  10. Cool stuff. Hypothetical and presently deemed logically impossible stuff, but cool nonetheless.
  11. interesting post. I find aeronautics fascinating and I enjoyed this.
  12. we have a dark future in front of us, that's for sure
  13. oxy126

    Photonic Boom?

    It happens in nuclear reactors too, because the water slows light down. They call it Cherenkov radiation, and it's pretty sweet.
  14. If a random star were to appear in our skies, and you asked an astronomer how far away it was, they couldn't give you an immediate answer. One thing I always took for granted was how these scientists were able to map the night sky, give us a detailed perspective on what was out there in the final frontier. Some of these methods (like how to determine how far away a star is) can be somewhat interesting. Using the right math, many people could triangulate the position of an object, as long there are a few known variables and objects in the field of view. However, on Earth, to calculate how far away a star is, through distances spanning hundreds of light years, it is very difficult, because the angles which are being dealt with are very small, and hence prone to error. However, given a 6-month span, our orbit around the sun gives us a much better distance to do this calculation with. Knowing such things as the precise time, radius of orbit around the sun, and the positions of other stars in the sky, we can calculate relatively well star distances. However, this only really works up to 400 light years (thanks, HowStuffWorks), because, while the 150 million kilometer difference in our position is a lot, with a star 10 light years away (still fairly close), the difference in angle is still miniscule, clocking in at just a few hundred-thousandths of a degree. Which is to says, that while the distances we get aren't perfectly accurate, for what they're worth they are pretty dang good. There are different, more spectroscopic and more accurate methods of determining a star's distance, that rely on standard gathered data for stars that work at all distances. But before this data was collected, really the only way to gather this data was through triangulation. That, simply put, means that olden astronomers, those like Galileo, were the ones doing all this tricky math. Cool stuff.
  15. The gravitational two-body problem is a popular concept in the study of planetary bodies. In essence, it models the paths taken by two massive objects orbiting around each other. Earlier today, I was thinking about our Earth's orbit around the sun, and how while it is easy to think that the Earth doesn't move the sun, it does. So while our solar system surely doesn't have only two bodies, I decided to assume it did (and with a perfectly circular orbit), and calculate just what the orbital radius of the sun is. Beginning this, I actually had no idea the gravitational two-body conundrum existed, so I tried to solve for part of it myself. Knowing the force of gravity on both objects (Gm1m2/r^2), and the centripetal force necessary to maintain said orbits (mv^2/r - note, however, that the r in both equations is not the same: the r for gravity is the sum of the radius of both bodies around the barycenter, or center of the orbit). Using this knowledge (and I won't bore you with the steps), I arrived at Ea/w^2 = Sb/v^2, with E=mass of earth, a=distance from Earth to barycenter, w=velocity of the sun, S=mass of sun, b=distance from sun to barycenter, and v=velocity of the Earth. However, I felt this required too many known values, and could be simplified. From there I looked into the laws of momentum. Knowing that the force of gravity was the same on both bodies, and that it acted (obviously) over the same time period, I deduced that the momentum imparted to both was equal. However, momentum is also mass times velocity. Using that knowledge, with my previously derived equations, I could further simply and eliminate my velocities, netting me, eventually, the distance of each mass to the barycenter (equivalent to the mass of the object times the radius between objects, divided by the sum of the masses). While you may not think this is too exciting, I found that deriving this, and then finding out I was actually right was interesting. All of these equations that were used were simple, but when applied together in the correct situation, they have the ability to solve more complex problems.
  16. Escape velocity, at the surface of the earth, is just about a whopping 11.2 km/s. This means that, to completely escape the force of earth's gravity, from the surface of the earth with the only outside for being gravity, you would need to be going this speed to escape (ignoring, of course, drag - drag forces at those speeds would rip a spaceship apart). So on my way to physics last friday I thought about how to reach those speeds, without the use of costly rocket fuel. One (although initially very costly solution) could be to have a giant underground tunnel, throughout the entire surface of the earth, that would accelerate an object over time using electromagnetism until it reaches those speeds. As long as the tube is in a vacuum, it is more than possible to do this. In order to keep an object in a circular orbit, we know that the centripetal acceleration must equal mv^2/r, and this net acceleration can only come from two other sources - gravity, at a constant 9.81 m/s^2, and the force generated by our electromagnetic coils. Assuming v is terminal velocity, E is the electromagnetic force, and r is approximately the radius of the earth, we get (11.2 * 10^3 m/s)^2/(6.371 * 10^6) = 9.81 + E. Solving for this, we can determine that E = 9.88 m/s^2, only a bit more than the acceleration due to gravity. If you could somehow construct this tunnel, it would be possible to bring objects up to speeds as high as this. Most of the time, for typical space missions, it wouldn't have to be quite so large anyways. The real issue is getting in out of the tunnel, and through the atmosphere. Going straight into the air at such speeds would destroy a fair chunk of the surrounding area, and most certainly the payload. You would have to create a giant vacuum tunnel through the atmosphere if you wanted this to work, which not only would look strange (it would be technically 'flat' - tangential to the point of release for the most part), but be very difficult to build. But in any case, it's wishful thinking.
  17. Over the summer, I learned a lot about light, and I welcome the opportunity to share that with you. One thing I learned about was how different light sources stacked up against one another. Most people know that incandescent bulbs (tungsten-halogen, the "normal" kind) are less efficient that LED or fluorescent bulbs, but don't know why. I'm here to alleviate that knowledge gap. The reason incandescent bulbs are inefficient is because they produce a lot of heat - not just their own heat, but rather they radiate heat, in the form of infrared light waves. Eventually, all of the energy that goes into heating up the tungsten filament does get radiated out, but usually not at visible wavelengths. When an object is heated (through the addition of energy, AKA Q = mc * delta t), it begins to reemit that energy at a variety of wavelengths, until all that energy has been dispensed of. The distribution of this energy, as a function of wavelength, follows (mostly) a blackbody radiation distribution curve (see below), which shifts as a function of temperature. Most of the energy for a tungsten bulb is in the infrared region, meaning it is never actually seen. With hotter objects, however, more of the light is visible, and shifted towards lower wavelengths, which is why hot flames appear blue to our eyes. A tungsten bulb is usually around 3300 degrees Kelvin, so a lot of energy is lost. However, in recent years, in attempts to save energy, other light producing methods have been pursued. One of these is the use of fluorescent bulbs, which rely on molecular excitation to produce light. As discussed in chemistry, electrons falling down an energy level emit photons of a very specific wavelength. Above is an example spectral distribution curve. As you can see, almost all of the emitted light is in the visible region, making it much more efficient. However, because these contained dangerous chemicals oftentimes, the concept of the LED was also pursued as a potential light source. LEDs (a topic to be discussed by itself), "force" electrons to change energy levels as they flow through a circuit, through (usually) a junction between different types of doped silicon. The spectral distribution for these is, like the fluorescent, confined to a short wavelength band (usually blue). However, using a phosphor coating, which will absorb and reemit the light at different wavelengths, the light is made to look more "white" (see below). That, in a nutshell, displays a variety of common lightings, and why some are preferred over others. I could go into more depth, but this gives a basic overview of how we light our world.
  18. oxy126

    Makin' Noise

    I'll play you some Brahms. He's pretty dank
  19. oxy126

    Physics Boarding

    nao give me your kinetic energy boi
  20. oxy126

    Makin' Noise

    Sometimes I like to sit back and pump some jams. Before the invention of all this modern technology such as speakers and cds and digital audio, such things just weren't possible. Music had to be performed. But with the invention of electrical speakers that all changing. People were able to finally jam out. The common speaker relies on the principles of electromagnetism. In the center is a magnet (attached to a speaker cone), surrounded by a coil. As the current through the coil fluctuates, the magnet and cone move, vibrating to reproduce the encoded sound. However, all things have inertia, so it can take time to reverse the momentum of the cone, creating a loss in audio quality in the event that the speaker cone is too heavy. Similarly, if the cone isn't stiff, it will delay its movement and creating quality losses that way as well. These losses are most noticeable with "harsher" waveforms (such as squarewave, which, as the name implies changes position very quickly at wave boundaries), or with more complex sounds, such as violin or saxophone. Because of these drawbacks good sound systems often have multiple speakers, all tuned to a different frequency. Subwoofers are typically larger because lower frequencies are less audible, and lower frequency waveforms are easier to reproduce in terms of speaker design. Tweeters are smaller for the opposite reasons - they need better accuracy because higher pitches involving larger shifts in momentum with respect to time, so they are typically smaller to achieve this. Also, because every material has a resonant frequency (where it will absorb a lot of energy), the materials in each are tailored to avoid this. Next time you're cruisin', bumpin' along to your favorite song, remember this. And invest in a better sound system.
  21. Boi it's a pleasure to be your classmate
  22. In the past few years, the Dyson Air Multiplier has revolutionized the field of recreational air transportation. It's for this reason that I feel it warrants a blog post, all to itself. Lauded for a lack of (visible) fan blades, it is safer than the more common axial-style fan. The Man Behind the Magic But how is this trickery pulled off? Allow me to explain. The Dyson Air Multiplier does, in fact, have typical fan blades. But instead of being open to the air, they are hidden in the base of the fan, and air intake is through the little gratings along the circumference of the tube. That air is then "pumped" through the upper ring and exits the fan. But then why is it called an "air multiplier"? Dyson claims that the fan outputs 15 times the input air volume, and it does (or at least comes close). It does this as a result of Bernoulli's Principle, which states that faster moving air has a lower pressure. Because the air in the center of the ring is slower, and therefore higher pressure, it tends to get "dragged" along behind the small amount of air that is output, bringing more air into the mix. Conservation of energy still applies, so yes, the air does get decelerated during this process to account for that. It still does have a fan in the base, which can be noisy in getting the air up to an acceptable speed to "multiply" it. But it is a unique and interesting concept nonetheless, and a mark in the record books for "fan"-atics like me.

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