For which reason the shock waves are produced?
If you mean aerodynamic shock waves, it is simple a function of speed and air temperature/density.Imagine a boat going across a still lake at speed, The bow wave is the same as the pressure wave forms as an aircraft goes through the sky.At the point when a boat gets up ‘on the plane ‘ and begins to ride over its own wake it is like an aircraft going supersonic.The shock wave is what happens when the boat wake hits the shore.A rough analogy but does that help?
An under water bubble collapsed with sound wave produces light. Why? Which phenomena involved ?
The phenomenon is called Sonoluminescence. The exact mechanism is unclear; see the Wikipedia article Mechanism of sonoluminescence for an overview of the key theories.But at a basic level, it’s not entirely surprising that high-frequency sound would produce light. The pulses of sound cause areas of high and low pressure. Within the low-pressure zones, small bubbles of near-vacuum can form, called Cavitation. The subsequent high-pressure wave forces the edges of the bubble together with a fair bit of energy. That energy transforms into heat. The total amount of energy isn’t high, but it’s all in a very small place, so the temperature is very large, in the thousands of degrees. And anything that hot will emit visible Black-body radiation.There’s a lot of uncertainty in the details of this mechanism, but it’s fairly certain to fall somewhere in this range.
What is the type of shock waves produced due to explosion at the bottom of water?
Most underwater blast scenarios happen in sea water not fresh or pure water. Salt, unlike water, readily absorbs neutrons into the sodium-23 and chlorine-35 atoms, which change to radioactive isotopes. Sodium-24 has a half life of about 15 hours, while that of chlorine-36 (which has a lower absorption cross-section) is 300,000 years; the sodium is therefore the most dangerous contaminant. These are generally the main radioactive contaminants in an underwater blast; others are the usual blend of irradiated minerals, coral , unused nuclear fuel and bomb case components present in surface blast nuclear fallout , carried in suspension or dissolved in the water. Thus plain distillation or evaporating water (clouds, humidity, and precipitation) purifies it of radiation contamination, including the radioactive salt.The effects of an underwater explosion depend on several things, including distance from the explosion, the energy of the explosion, the depth of the explosion, and the depth of the water.Underwater explosions are categorized by the depth of the explosion. Shallow underwater explosions are those where a crater formed at the water's surface is large in comparison with the depth of the explosion. Deep underwater explosions are those where the crater is small in comparison with the depth of the explosion, or nonexistent.The overall effect of an underwater explosion depends on depth, the size and nature of the explosive charge, and the presence, composition and distance of reflecting surfaces such as the seabed, surface, thermoclines, etc. This phenomenon has been extensively used in anti ship warhead design since an underwater explosion (particularly one underneath a hull) can produce greater damage than an above-surface one of the same explosive size. Initial damage to a target will be caused by the first shock wave; this damage will be amplified by the subsequent physical movement of water and by the repeated secondary shock waves or bubble pulse. Additionally, charge detonation away from the target can result in damage over a larger hull area.Underwater nuclear tests close to the surface can disperse radioactive water and steam over a large area, with severe effects on marine life, nearby infrastructures and humans.The detonation of nuclear weapons underwater was banned by the 1963 Partial Nuclear Test Ban Treaty and it is also prohibited under the Comprehensive Nuclear-Test-Ban Treaty of 1996.
What causes shock waves?
Shock waves are caused when the wave source travels faster than the wave speed in that medium. Mostly every boat wake is an example of a shock wave. Supersonic aircraft generate shock waves as well. Shock waves of light can also be generated when high speed particles enter a medium such as a liquid where the speed of light is lower than normal. This is called Cherenkov radiation.
What is a shock-wave and how is it formed?
Shockwave.! SHOCK WAVE is a thin transitive area propagating with supersonic speed in which there is a sharp increase of density, pressure and speeds of substance. Shock waves arise at explosions, detonation, supersonic movements of bodies, powerful electric discharges etc. Let's consider an object which moves with speed of sound (the plane, for example). At each moment of time it will radiate a circular sound wave. Because the speed of source coincides with speed of sound, emitted waves superpose each other and there is a jump of pressure (front of a shock wave) ahead of source as shown in animation.If the source moves with speed less than speed of sound, then the shock wave is not generated. Ordinary sound waves propagate forward in the direction of source motion, overtaking it, and back. Due to Doppler effect the still receiver located ahead a source detects a sound with the greater frequency, than emitted. If detector is behind of source, then the received frequency will be lower then emitted. In animation the rings show the surfaces of equal phase in the sound wave generated by a source. We see, that ahead of a source the density of such lines is more than behind of it. Because the speed of sound relatively the media is equal in all directions, the frequency of sound ahead a source and and behind of it will be different.Let's consider a case when the source of a sound moves in the environment with supersonic speed (in animation the source moves with double speed of sound). In this case sound waves can not overtake a source and for this reason there are no sound waves before a source, they appear only behind of it. Sound waves arising behind a source superpose with each other and form in space a conic surface of high pressure. This surface is a shock wave. It is easy to show, that a sine of the angle formed by front of a shock wave with a direction of movement of a source is equal to the ratio of speed of sound to speed of source (i.e. it is the reciprocal of Mach number).
Do submarine SONARs cause giant water shockwaves?
No, they do not. What they do is actually far worse.To ocean-dwelling creatures who use their sense of hearing to avoid predators, find food, and communicate with each other, active SONAR sounds like a busy highway or an airport does to us land-dwellers. In the vicinity of a military exercise, these creatures are overwhelmed by the noise and cannot live their lives in any kind of a normal way. Whales and other sensitive marine mammals have actually been known to beach themselves in order to get away from the racket. In other words, the noise is loud enough to drive them mad.If SONAR caused “giant shockwaves” in the water, we would notice the problem and either redesign our systems or use some other technology to accomplish the purpose. But because it simply generates noise at frequencies that our air-adapted ears cannot hear, we can and do ignore it and (consequently) ignore the terrible damage it does to all of the ocean-dwellers that depend on sound for their daily lives.It took a years-long and very expensive lawsuit against the U.S. military to even get them to acknowledge this problem, and they are still refusing to fully implement procedures and guidelines that would keep their operations and training exercises from causing widespread harm to marine organisms.
Why is light produced when an underwater bubble is collapsed with a sound wave?
Sound always generates some amount of heat when it passes through a medium. Things that are warm always produce some amount of light (through blackbody radiation). But the mystery here is why so hot?There is some controversy about exactly how hot these collapsing bubbles get, and exactly why they get so hot, but it is not surprising that there is a great deal of energy that must be thermalized in a very short period of time.The concept of a water hammer is well know to be able to cause damage to pipes when a column of water is caused to come to an abrupt stop by shutting off water flow. In the case of sonoluminescence, the water hammer is travelling inwards from every direction and it collides with itself rather than the end of a pipe. This leads to formation of an extremely high pressure in the last few microns of closing, and that increase in pressure is what drives the increase in temperature.The exact source of the light varies depending on the working fluid and the gasses dissolved in the water. Some of it will be ordinary blackbody radiation, but the dominant source will be light coming from thermally ionized molecules re-collecting lost electrons. When those electrons drop from higher electronic levels (of from the free state) down into their bound states they release photons in much the same way that a neon lamp does.By looking at the spectrum of the emitted light, researchers have been able to make inferences about the temperature that must have existed in order to excite the transitions observed.