We all know that bullets and planes have broken the sound barrier buy passing the speed of sound. What would happen if they developed a torpedo that could break the speed of water?\n\nIt’s all fluid dynamics right? Is it possible?
213857
You are right; it's all fluid dynamics, and even though your idea is still a fiction, the technology that could produce it is real enough. At least one Russian submarine is armed with torpedoes that exploit it. The same idea is being used to make guns for destroying underwater mines, and it could double the speed of surface vehicles such as hydrofoils. Most remarkably, it could produce an underwater vessel capable of traveling at thousands of kilometres an hour while remaining almost entirely dry. For the key to this technology lies in the humble bubble. \n \nThe problem holding back ordinary torpedoes was drag. Any object, no matter how streamlined, suffers resistance as it moves through a fluid. In the early 1960s, Mikhail Merkulov at the Hydrodynamics Institute in Kiev realised that the solution lay in a phenomenon called cavitation. It was a daring idea, because naval architects usually see cavitation as a menace, rather than something that works to their advantage. But supercavitation is a different matter - under certain conditions, a single bubble or supercavity can be formed, enveloping the moving object almost completely. \n \n Supercavitation is hard to achieve - the body has to be going pretty fast, at least 180 kilometres an hour, or 50 metres per second and the shape of the nose also has to be right, say researchers. Rather than being streamlined, a supercavitating object needs a flat nose. Then, at high speeds, the fluid is forced to flow off the edge of the nose with such speed and at such an angle that it can't wrap around the surface of the body. A supercavitating body has extremely low drag, because its skin friction almost disappears. Instead of being encased in water, it is surrounded by the water vapour in the supercavity, which has much lower viscosity and density. So in a supercavitating vehicle, only the nose of the craft causes significant drag, because this is the only part of the body actually in contact with the water. \n \nAccording to Mark Galeotti, a defence expert at Keele University in Staffordshire, prototypes of the torpedo appeared in the 1980s, but there was still plenty of work to be done. "It was only in the early 1990s that the Russians were in a position to produce a proper working torpedo," says Galeotti. Called Shkval, meaning squall, it is said to be capable of speeds as high as 500 kilometres an hour. It is fired like an arrow from the submarine, possibly with a mechanical catapult. That gets it moving fast enough for the cavity to form, so that its rocket can be lit. The Russians had built themselves a formidable weapon. Shkval leaves enemy torpedoes standing, and can knock out an opposing sub before it has time to react. It could even be used defensively to intercept enemy torpedoes. \n\nJust a few years after Shkval's debut, NUWC (USA) researchers announced they had gone supersonic. An unpowered projectile, with a carefully designed flat nose and fired from an underwater gun, broke the sound barrier in water. That's nearly 5400 kilometres per hour--or 1.5 kilometres per second. Lacking any onboard power to sustain its motion, the shell slowed rapidly, but this was still a vivid demonstration of the speeds that supercavitation makes possible. Already they aren't very far off the 2.5 kilometre-per-second speed record for conventional munitions in air, and scientists have calculated that their supercavitating projectiles should be able to match or even surpass this. \n\nBut there are plenty of technological hurdles. One thing still needed is a powerful and compact propulsion system. An aluminium-burning rocket is one answer. It would use water as its oxidiser, and so wouldn't need to carry oxygen. The problem with aluminium has been that unreacted fuel quickly becomes coated with aluminium oxide, inhibiting any further reaction. To avoid this, powdered aluminium can be injected into a vortex of water, which keeps the burning, molten drops apart. Alu
286078
Wow. Science FICTION remember. Lucas has actually talked about that decision.  It was done for effect. Once he decided that there would be sound in the vacuum of space he had to keep the idea going for the sake of continuity. How good would the opening scene have been if we sat in the cinema with that huge space ship flying in overhead, laser canons firing explosions all around and no sound? Sound heightens the experience. So while he was aware that there is no sound in space, he decided in his universe, there would be.
418150
I wondered where you had been.  You think way, WAY outside the box, don't you!?  I thought the question was pretty disgusting until I read the additional details.  What an imagination.  My only thought is, that's a lot of contained gas and wouldn't the funnel explode?
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I too would be veeerrrrry interested in seeing some evidence for this claim from a non-creationist source. I keep an eye out for this sort of thing out professional as well as personal interest and I can't recall seeing anything like it.\n\nRoger are you absolutely certan that you haven't misundertsood the phase velocity experiments of Wang? They were done around that time (published 2000 IIRC). But they never shattered the speed of light or anything like that, no  did Wang et al ever make such a claim.\n\nTo help you out Roger, folow the link below? Is that what you arehtinkng of? If so you have misunderstood the results entirely.\n\n" Wang et al. (2000), who produced a laser pulse in atomic cesium gas with a group velocity of 310+/- 5 C. In each case, the observed superluminal propagation is not at odds with causality, and is instead a consequence of classical interference between its constituent frequency components in a region of anomalous dispersion (Wang et al. 2000)."\n\nIOW the speed of light wasn't exceeded by a particle, massless or not. It was the speed of the frequency change wihtin the medium that was 300 times faster than light. Perhaps the easiest way for a layman to understand this is to imagine one of those Newton's Cradle's toys. (see link 2). \n\nWhen you let go of one ball the motion is tranferred through the two intervening balls to the other end, causing that ball to fly up. That motion is is transmitted at near enough the speed of sound. IOW when the dropped ball hits the suspended balls the motion is passed along at the speed of sound. \n\nBut, and this is important, the ball itself wasn't travelling at the speed of sound. Nor did the ball on the end fly out at Mach 1 just because the motion was tranferred at MAch 1. The motion of the drooped ball was transferred at Mach 1, but at no stage was the ball or anyhting else actually travelling at Mach 1.\n\nWang's experiments did approximately the same thing using photons rather than metal balls. By some very clever work they managed to induce a phase change within the Cesium medium. In essence the Cesium atoms became the middle balls in newtons cradle. When light  hit an atom on one side it caused a phase change that was then passed on to the next atom, then the next and so forth, all at 300*C. But it was the phase change that was moving at that speed, not photons, not even electrons, just a phase change.
528734
Gravity only "slows" the bullet during 1/2 of its total trip, during the other half, gravity accelerates the bullet.\n\nAs the bullet rises into the air its velocity is continually decreasing as the force of its own weight (force due to gravity) as well as the force of air resistance, act to accelerate it downward.  At some point the bullet will come to a stop and then begin falling.  Afterward, gravity acts to increase the bullet's speed while the air resistance works in the opposite direction.  The magnitude of the force of air resistance depends on the speed of the bullet (the faster it does, the harder the air pushes back on it).  Eventually, the bullet will reach what is known as the "terminal velocity", where the force of gravity equals the force of air resistance, and the bullet stops accelerating (net force = 0).\nThe terminal velocity for an object depends on several factors including the object's mass and shape, as well as the density of the fluid it is moving through.  The terminal velocity for a bullet is lower than the speed at which it comes out of the gun in most cases, so the bullet will never be traveling as fast as it was while leaving the barrel when it hits the ground...but still, I would still not want it to hit me.
455153
If your question is really in a vacuum then no. If, however, you mean in space, then yes, it can. See http://www.nasa.gov/centers/goddard/universe/black_hole_sound.html. \n\nExcerpt: "You may be wondering how a sound wave can travel through space. After all, sound waves require some sort of stuff to move through. This stuff, called a medium, can be air, water, or even solid rock. And space is thought of as lacking any medium because it is a vacuum.\n\nIn fact, space is not a pure vacuum but rather it contains stray bits of stuff -- gas atoms and dust of varying amounts. In the case of the Perseus cluster, the gas throughout it serves as the medium through which the sound waves coming from the central black hole travel."
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Not necessarily. If your theoretical gun shoots a bullet that reaches escape velocity [1] (the speed something needs to travel to beat Earth's gravity), it can overcome the Earth's gravity [2] and fly off into space.\n\nHowever, I know of no such gun. Only rocket engines [3] are able to do this, because they sustain and increase their speed by burning fuel. A bullet has nothing to keep its speed up once it leaves the gun.\n\nSo the answer is, "Yes, the bullet comes back down." The bullet is always beholden to gravity, even before it's fired. You can view gravity as an invisible string always pointing to the center of the earth, always being pulled. The instant the bullet leaves the barrel of the gun, it will be constantly slowing down due to gravity (and air resistance).\n\nAnother interesting idea is this: If you were to take a gun and fire it horizontally, and at the same instant drop a rock from the same height as the gun, which would hit the ground first? The bullet or the rock? \n\nThe answer is that they both would hit the ground at the same time. The bullet would just be several hundred feet away when it hits. Both are affected by gravity's pull, and approach the ground at the same speed.
446948
“The Otter,” a 6’5” by Rich Pavel concave stringerless, “The Disk,” a Dave Parmenter bellyboard designed for a certain boutique wave, and “The Neumatic,” an inflatable air mattress all claw their way to the surface for this (hopefully) recurring look at non-traditional wave craft. What might we unearth next? Plenty. The New Democracy in equipment is revving, and we struggle to think of a downside.:-)
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Into the abyss of course........:)\n\n*runs to the blog to go copy her answer from there*\n\nLovely picture by the way, but it has scared me from ever boarding the Mayflower. Thank goodness I'll never have to. I would have looked horrendous in the pilgrim shoes anyway. But enough rambling......let me get to the question.\n\nThe ships would all fall into the abyss. What if....the fall was neverending? What if they just kept falling with no where to land? would the water keep running too? would it lead to another land? Is this where "neverland" is? Or do we fall and fall into a nothingness? Or will we fall and land on the River Styx? \n\nWe know the ocean water has to return other wise the earth would be drained and before long draught would be the next issue after global warming. So my thoughts are crazy but that the water falls and falls and falls until it hits a warp that sucks it back up and into the earth yet again similar to the way a fountain works. A never ending cycle. But if so........what could possibly be at the bottom of the abyss??? One shall never know. *sigh*
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Yes, the discover channel show myth busters actually did a show on this once after someone asked the same question because they watched a cannon ball bounce in a war movie.  Cannon balls are very heavy...so if they hit a soft or low density surface like dirt or grass they will generally make a divet and come to rest where they land.  However, if shot from a low trajectory they CAN skip...like skipping rocks on a lake...in fact if shot at a fast enough speed they can even skip ON a lake themself.  When dropped from ontop of the myth busters studio building the cannon ball hit the concrete, did some major damage that made Jamie really mad and rolled off the sidewalk BUT fascinatingly enough...slow frame film showed, afterward, that when the cannon ball rolled off the sidewalk it actually bounced once...a tiny tiny bit.  They also did some research with revolutionary and civil war historians and found that a VAST majority of cannon ball injuries from that era actually CAME from low flying cannon balls taking off legs and such just like in the movie.  In fact the true myth wasn't the bouncing of cannon balls...it was the big explosion of dirt and shrapnel that fly out and take down 15 guys around it.  Cannon balls dont break up when they land like grenades and bombs...so that doesn't really happen.  Sometimes if the ground is soft enough there will be a big dust cloud but unless the ground is covered in nails and scrap metal...there won't be any shrapnel in the dust cloud to cause damage.  Most of the time, though, the ground was uncultivated so it was generally hard enough that a cannon ball landed with a thud and stayed there.  According to the experts there were even opportunities after a battle for the winning side to go out and gather up all the expended canon balls off the field and re-use them.  The single greatest danger from cannon balls at that time was actually the low flying bouncing ones that skipped over the ground and ripped legs off as it went...(by the way in the scene in The Patriot where it bounced high enough to take the guys head off...that was busted.  They're too dense to actually BOUNCE like that...they more or less SKIP which is still a form of bouncing but most injuries were leg injuries NOT decapitation by cannon ball)...there was a low chance of a cannon ball landing directly on a person but the odds were outstanding...I can't recall the actual numbers now but I know when I watched it...my jaw dropped.
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As with any thermonuclear explosion, you obtain a huge amount of radiated energy in a very small location in a very small amount of time.  This radiated energy would be absorbed by the surrounding ocean water very quickly.  This would cause a HUGE amount of water around the detonation site to flash-boil and expand rapidly.  This would create a propagating hydrostatic shock wave that would be felt all throughout the Pacific, mostly in the form of tidal waves.  These tidal waves will likely be fairly small, however depending upon the composition of the ocean floor, it may also let loose alot of rock and cause some underwater avalanches (another common source of tidal waves, esp. the bigger ones).\n\nDepending upon the depth of the detonation, very few of the radiated photons may actually reach the surface, and thus almost all of the energy will be consumed by water.  Besides no "blinding flash", this would also mean that the visible "water explosion" made up of mostly vapor would be larger than the equivalent land- or airburst vapor cloud.  If close enough to the surface, the flash-boiled water would quickly rise and break the surface with a large gaseous explosion, and the vapor would climb into the air and spread once it achieves altitude, so yes the "mushroom cloud" will still form.  If it were very deep, though, the gasses would eventually spread and, to some extent, dissipate, resulting in just a lot of surface turbulence and foamed gasses.\n\nDo some research on "Operation Crossroads", which were two U.S. nuclear detonation tests in 1946.  ABLE was an airburst at 158m, and BAKER was 27m underwater (yes, super-shallow, but it gives you a fair starting point).  There have been other underwater nuclear test detonations by various countries, but their speifics escape my memory at the moment.  :p
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When the Germans first introduced U-boat warfare in WW1 ( 1915) the British Navy ( the US wasn't in the war then so it was an all R.N. show) hadn't a clue as to what to do........it took a while to develop the depth charge....and even longer to developer an underwater listening gear so you could get an idea of where the bloody thing was to drop the charge)( further aside.at first it was just a listening device to hear the U boats propellers ASDIC from Allied Submarine Detection Investigation Committee....SONAR Sound Navigation and Ranging, which put out a blip of sound that reflected back.....the bleep bleep bleep noise in all the sub movies came much later.....)\nso before there were depth charges the Royal Navy had to resort to some desperate improvisations, and yes, dragging hooks to grab a sub was one of them. Not very successful as you can imagine. Less successful was a scheme where two guys in a motor launch would chase a periscope; one guy would put a hood over it, the second would smash it with a hammer.\nOh,a nd by the way.as submerged torpedo shooter, the German U-boat force reduced England to 6 weeks of food as of Jan 1 1917 and damn near won the war for the Kaiser.
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I think it would land behind you because as it rises, the rotational speed of the bullet around the earth would have to increase in order to keep up with you because it's going around a larger circle.  Of course, if you're going around a sphere, that could also be considered to be in front of you.  Also, I doubt that the bullet would fall at the same speed that it was shot.  I don't think that gravity would get it going as fast as the gun did.
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I have some experience with designing lightweight missiles (Nerf type guns specifically) and I can tell you that there are 3 main items of importance when it comes to getting the maximum range possible:\n\n(1) Have a set of 3 or 4 fins that poke out to just about the same diameter as the body of the rocket if the rocket tapers in at the back, or about 25% to 50% greater diameter than the body of the rocket if it does not taper.\n\n(2) make sure you have no "shelves" in the design.  "Shelves" are rear-facing step-like features that create suction as the rocket is flying through the air.  Imagine a bullet flying through the air, the bullet is basically cylinder-shaped but it is pointed at the forward end.  The rear end is flat.  This flat creates a shelf, and a region of suction forms there which slows the bullet down.  When you are dealing with something low-density like a soda bottle rocket, this suction has a much more noticeable effect than it does for higher-density projectiles like bullets.  But even with bullets, they use a shape called a "boat tail" to overcome this -- see the "Rifle Bullets" section of this website for a picture of what I mean:\nhttp://matrix.dumpshock.com/raygun/basics/bullets.html\n\n\nFor a what-not-to-do, take a look at these missiles:\n\nhttp://www.amazon.com/gp/product/images/B0002FYR0M/ref=dp_otherviews_2/002-1250901-3240058?ie=UTF8&s=sporting-goods&img=2\nNotice how the back end is flat?  That is where all the suction happens.  If they had a way to make those missiles taper together at the tail, they would go a lot farther.  Since a soda bottle tapers at the mouth (which is the rear when launched as a rocket), you want to maximixe this effect.\n\nhttp://ec1.images-amazon.com/images/G/01/ciu/e7/fc/a232d250fca071ddd6b17010.L.jpg\nNotice how this one not only is flat at the rear, but it also has a "shelf" feature that goes all the way around it, at the back side of the yellow warhead section.  That will create a lot of suction too.  If that were tapered into the body like the rightmost missile in this picture, it would go a lot further:\nhttp://en.wikipedia.org/wiki/Image:Titan_Missile_Family.png\n\n(3) Nosecone -- ideally for a low-velocity low-density missile like a soda bottle rocket, this should be rounded.  Like the ones at the top of this webpage about soda bottle rockets:\nhttp://waterrocket.uh-lab.de/backglide.htm\n\nYou can probably get some really good nosecones for relatively little money at a local hobby shop, in the model rocketry department.  Failing that, look for a thin hard-plastic ball that you can cut in half.  Some soda bottles already have rounded ends, but these are becoming very rare now since they were more expensive to make than the ones with flat ends.  If you can't find any good round nosecones, you can make a cone-shaped one by cutting a big circle out of construction paper and then cutting a "pie slice" out of that circle.  Now you can easily roll up the remaining circle section into a pointed cone.  Play around with it until you have reduced it to the least amount of paper needed to achieve the desired cone, because any extra paper is just weight that must be moved and yet won't help it fly any better.\n\nHere are some great web pages for this fun sport -- including one from NASA!
535693
Sound is a type of longitudinal, mechanical wave. They need a medium to propagate and will not travel through a vacuum. Sound travels at different speed in different media. The speed of sound is determined by the density (ρ) and compressibility (β) of the medium. Density is the amount of material in a given volume, and compressibility is a meaasure of how much a substance could be compacted for a given pressure. The denser and the more compressible, the faster the sound waves would travel. Therefore, the speed of sound is about four times faster in water than in air. The speed of sound in a medium can be determined by the equation  …\n\nv = (βρ)-1/2\n\nWhere …\n\nv is the speed of sound,\nβ is the bulk modulus of elasticity, and\nρ (rho) is the density.\n\nThe speed of sound can also be affected by temperature. Sound waves tend to travel faster at higher temperatures. I have found different values for the speed of sound in water in different sources. They range from 1450 to 1498 meters per second in distilled water and 1531 m/s in sea water at room temperatures (20 to 25 °C).
63113
First of all, IT'S GRAVITY BABY! Not really, but it does play a part. It's mostly the force of the wave, working with gravity to move that board at that certain speed.\nsomewhat like that
192994
the made airguns during wwii as experimental weapons. germany even shot a few to no effect. aim was to create a vortex to disttrub aircraft. theory was sound, and there is a less than half size model or two about doing special effects, but the german version failed