What is Shock: Definition and 237 Discussions

In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium.For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by constructive interference.
Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance.
When a shock wave passes through matter, energy is preserved but entropy increases. This change in the matter's properties manifests itself as a decrease in the energy which can be extracted as work, and as a drag force on supersonic objects; shock waves are strongly irreversible processes.

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  1. Antitank_Borshch

    Help me come up with shock effect preventing technology (sci-fi book)

    There is a problem in my technological concept that does not allow the normal development of the plot of the book. It takes place on an ocean planet where being above sea level is absolutely dangerous with the level of technology that exists there. So all combat operations there take place...
  2. S

    Thickness of normal shock zone (e.g. in nozzle)

    Under certain conditions, a supersonic flow in a nozzle will result in a "normal shock", an abrupt change in pressure and velocity. In the videos I've looked at, they draw the P and v graphs with a vertical step at that point. But in practice, I assume there will be a non-zero transition zone...
  3. Quotidian

    A Radiation Shock Too Powerful to Examine (EMP)

    Hi all - I'm not a physics grad, my knowledge is limited to whatever I can glean from popular science publications. Anyway, I'm crafting a hard sci-fi story - 'hard' because it's written to seem kind of plausible, or at least not outrageously surreal - no shape-shifting or anti-gravity or...
  4. kma

    Can wet hair cause an electric shock if it gets into outlet/power cord

    Hi I have a very random question I would like to ask. Say if someone just got out the shower and either plugged something into the wall, or plugged a high voltage power cord into a device. In the process of doing so a small clump or strand of their wet hair manages to get into the socket or the...
  5. agnimusayoti

    What is the mathematical model for a traffic shock wave?

    This was a Halliday Resnick Problem on the linear motion. I could have see the solution but I was not satisfied because I have not get the idea behind the solution. Could you please help me to explain what is exactly the problem is? Or, how to model the shock wave? So that I can make the...
  6. B

    I Shock Load on Rope: Weight Limit Analysis

    Hello, I’m not sure if the proper term is shock load. If a person is using a device and rope to lower themselves from a high point and they’re descending fast and then suddenly stop does that create a shock load? The device attaches to the rope and when a person squeezes the device it allows...
  7. H

    G-force to pressure relationship inside a shock wave

    I need some help understanding shock waves, particularly the units of measure related to their pressure. Shock waves are frequently quantified as multiples of G, the gravitational constant. I need to understand how the G measurements related to the instantaneous pressure within the wave as...
  8. G

    I What is the speed of a shock wave?

    There is lots of good information online about shock waves but I'm not finding what I want. If dynamite has a detonation rate of 6800 m/s does the shock wave travel at 6800 m/s? Is sound we hear 1 mile away the shock wave or the sound? What speed is an atom bomb shock wave? This large horn...
  9. mozer911

    How Can Comsol Model Time and Space Varying Pressure in Laser Shock Peening?

    Hello, I am trying to learn comsol but I couldn't find how to apply the pressure that changes respect to time and space. I have pressure function from articles that I read but couldn't implemented on comsol, and in most studies people make the simulation with Abaqus software so I am not sure...
  10. B

    I A Question About Shock Waves From an Airplane

    The elementary treatments I've seen show the shock wave spreading out in spheres centered on the plane and growing in radius at the speed of sound. So, clearly, the shock wave is sound, but what sound? What is it the sound of? In order for the plane to give off sound, it has to be making a...
  11. rudransh verma

    Car traffic producing shock wave

    I don’t get where exactly the lengths start and end in figure.
  12. K

    A Thermal shock wave question from my hydrodynamics simulation

    This is a fluid dynamic simulation. The top area has 100 degrees Celsius. The bottom area has 0 degrees Celsius. And both are filled with an ideal gas which is 1-atmosphere pressure. Two areas are connected through the left small line. Another part is blocked. So heat transfer can only happen...
  13. S

    What are typical Pressures in a test section of a shock tunnel?

    I'm writing a Matlab script to calculate various properties in a shock tunnel. While this might sound silly but I am not well acquainted with the subject and have very few resources to compare. For a mach 6 test section is it reasonable to have a freestream pressure as low as 305 Pa?
  14. M

    Oblique shock waves: how to find the wedge angle for trailing shock?

    Hi, I have a question regarding oblique shockwaves. Question: How can we determine what the wedge angle is for the shockwave in a situation? Context: This problem here shows an oblique shock wave on the trailing edge of the body and it simply states that the wedge angle is 6 degrees. Why is...
  15. FEAnalyst

    Design of welds under dynamic (shock) loads

    Hi, in the books about the design of welded connection, we can find detailed description of calculations for static and fatigue loads. But what about the other type of dynamic behavior - shock ? As an example consider welded parts of the tow hitch used to free vehicles stuck in mud. Of course...
  16. T

    Can a non-energized electrical component deliver a shock?

    I'm not an electrical engineer. I'm a truck driver. So please don't expect me to know much about electricity. This is a serious question. If an electrical part (such as the contacts of a contactor) has no voltage, can the electrical part shock a person while the electrical part has no voltage?
  17. E

    Required time and distance calculation of a shock wave

    I draw this picture in order to solve this problem. My first attempt was find the hypotenuse of the triangle and divide it by the speed of sound wave. d=a/sin(θ) d=4483.43m t=d/c=13.07 sec However, I am not sure whether I did it correctly or not... It looks the time is too big as an answer... I...
  18. jaumzaum

    Why can shock waves condense water vapor?

    Why can a shock wave condensate water droplets in the air and produce the visible vapor cone that we see when objects move faster than the speed of sound. Also, does this condensation happens only when the object is moving with a velocity greater than sound velocity? I don't understand the...
  19. theudster

    Effects of hypersonic speed on the behaviour of normal shocks

    I am learning about hypersonic flow now and there seems to be a lot of discussion about the effects on oblique shock as the Mach tends to be very large. I was wondering what happens to the normal shock as the Mach number tends to be high and I can't seem to find anything about it. Is it because...
  20. B

    Focused Acoustic Shock Wave Device for Generating High Pressures

    I am trying to come up with a design for a device that can generate very high and very brief waves of pressure directed at a 1 mm diameter target (shown as "E" in "Diagram.PNG") housed in a steel support structure "D". The idea is to accelerate hammer "A" towards anvil "B" in a vacuum tube. The...
  21. J

    I How do waves following a shockwave catch up to the shock wave?

    I was in an argument about a jet engine and I was arguing that since there is a cutoff in terminology what would kill someone approaching a engine is not technically sound, but a shock wave, (I'm probably wrong about this, but that's not the question). That got me wondering how waves can catch...
  22. B

    Shock wave through a liquid metal filled steel tube

    Would an A36 steel tube filled with liquid mercury be able to transmit a shock wave longitudinally through the liquid mercury with a peak pressure higher than the yield strength of the steel tube? My thinking is that since the shock wave is traveling normal to the tube wall, it should not be...
  23. X

    B Hypersonic aircraft shock layer color

    As a lot of people know, when things go hypersonic or even orbital velocities in the atmosphere, it’s going to get hot, scorching hot. The air emits black body radiation that are at the red spectrum (around 2000 to 3000 kelvins) sometimes goes yellow (5000-8000 kelvins maybe?) at re-entry...
  24. T

    Shock Wave Front: How Does Source Movement Create Waves?

    So when the source is not vibrating, it is not setting waves due to vibration? But it is moving so it is still causing disturbance in the medium ... And I happened to read that if the source is moving faster than the speed of sound, a shock wave is set up. How ?
  25. J

    B Coil + zinkplate + copperplate + 9V battery = shock

    So I just connected a zinkplate and a copperplate in series with a battery 9v and a coil(with a an iron core). All the parts are from a set bought for learning about electricity. Since I was a kid I have many time put the + and the - of a 9V battery on my tongue, and felt the electricity. So...
  26. Superposed_Cat

    How can C4 be detonated by heat or shock, only by electricity?

    I was thinking about electroactive polymers, and wondering if any exist that are immune to high temperatures, and although explosive decomposition is a completely different subject, it got me thinking about c4. Chemically speaking, what gives a compound such as c4 the ability to not detonate...
  27. Physics Dad

    Question regarding supernovae shock breakout

    Hi, I am currently studying for a masters in Astrophysics and am in my Stellar Atmospheres module. One of the questions I have been asked is with regards to the shock breakout of supernovae. Basically, the question is which type of stars show the strongest shock breakout and why? My thinking...
  28. F

    Shock wave system of equations

    Homework Statement This is Rankine-Hugoniot conditions at a hydrodynamic shock front. Where P2=0 v2=0. The problem is attached. I need to solve a system of equations. I thought it would be relatively straight forward solving for the three unknowns but I'm struggling. I know it's possible to...
  29. TechTree

    Why did a 230v electric shock not hurt?

    Okay here's an example of what not to do when working with 230v... So I was about to repair some outdoor lights so I went to the circuit breaker panel and switched off all the power in that area for safety. I began to remove the light and disconnected the wires, then I was about to install the...
  30. M

    Comparison of thermal shock profiles

    Could someone help me in comparing 2 different thermal shock test profiles effect on a component. The 2 profiles are varied in deg C /min change and also the dwell time in low and high tempwratures. Any references are highly appreciated. Thank you
  31. P

    Medical Eddy Current Hazards: Magnetic Field & Human Body

    Suppose a 10k Gauss 3in diameter sharp magnetic field is made & collapses completely thru a standing human human body somewere made by an external electromagnet.. The electromagnet is held horizontally and not vertically against body. Is this hazardous? Can it become hazardous after some...
  32. D

    Single phase AC 3 wire neutral conductor shock potential?

    I have a question with regard to split single phase (in United States) electricity. I understand that there are 2 hot legs each 180 degrees out of phase at +120v and -120v (240v between hot legs) going from transformer to breaker box and a center tapped neutral Earth bonded wire at 0v with...
  33. G

    Skin effect and electric shock question

    recently i saw a thread where skin depth was mentioned (I guess in one of my own threads) and then it got me thinking, well imagine we have a rather thick wire thick enough so that for a given frequency there is almost no current running in the middle of the wire due to skin effect. let's take...
  34. R

    Amplitude problem — Car shock absorbers going over a bump

    Homework Statement -(View image attached)[/B] A driver drives a car.The road has periodic small bump of 5 cm height and a distance of 5 cm. Car's shock observer works fine,damping the deflection to half each oscillation.Their length is 20cm increased if car weight(1500kg) does not...
  35. L

    I Shock crossing probability for isotropic particle flux

    Hi there, I am currently trying to understand the theoretical frame work of diffusive shock acceleration. I am having trouble understanding a step in the derivation given by drury 1983 (http://www.oa.uj.edu.pl/user/mio/Ast-Wys-En/Literatura/drury.pdf). In the derivation of eq. 2.47 it is stated...
  36. evinda

    MHB Solving the Shock Wave Problem for $u_t + uu_x = 0$

    Hello! (Wave) I want to solve the equation $u_t+uu_x=0$ with the initial condition $u(x,0)=1$ for $x \leq 0$, $1-x$ for $0 \leq x \leq 1$ and $0$ for $x \geq 1$. I want to solve it for all $t \geq 0$, allowing for a shock wave. I also want to find exactly where the shock is and show that it...
  37. H

    Plasma ball electric shock mystery

    Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?
  38. Emellish

    Elimination OF Abrupt Mechanical Shock Loading

    It's a problem of reducing an abrupt shock load as an 850 kg runaway machine trundles down ramps, and comes to an abrupt halt at the end of its tether fixed to a van's tow hitch. Ramps fixed to the van's rear door sill incline at 20 degrees to ground level and their length is 2.5 metres. I...
  39. Z

    Best material for a shock resistant phone case

    Hey! What do you guys think is the best modern looking material for a shock resistant phone case? I've been snooping around and stumbled upon a material called Carbon Nanotube, from the looks of things it looks quite ideal. What do you guys also think about Carbon Nanotubes? My idea is to...
  40. F

    Will this man get an electric shock

    If a properly insulated man touches with one hand +ve terminal of a 120 V battery and with another hand -ve terminal of (Edit: an another) 120V battery (two batteries are totally isolated, not connected in any way) then will he get electrical shock ? ( I am guessing , not). But if -ve terminals...
  41. A

    What is happening in this fluid dynamics problem and how can we approach it?

    Homework Statement Problem: https://imgur.com/a/ppDy6 Calculate the fluid speed at a certain point Given fluid and sound speed before the point Length of the conduct 2. Useful Equations: Uniformly accelerated motion(my solution) I have been studying this problem it for some time, have...
  42. A

    Stagnation pressure across a normal shock wave

    A body is reentering the Earth's atmosphere at a Mach number of 20. In front of the body is a shock wave. Opposite the nose of the body, the shock can be seen to be normal to the flow direction. Determine the stagnation pressure and temperature to which the nose is subjected. Assume that the air...
  43. M

    Work Energy Equation Help (what size shock absorber to use)

    Hi everyone. I'm trying to work out what size shock absorber to use. It's going under a seat so just the weight of a man really that it has to support. I've found a website showing the equations I need but I'm not sure about one of the steps. In step 2 it asks force output of the motor/drive...
  44. berkeman

    Why don't Marinas have GFCI protection to prevent Electrical Shock Drowning?

    There have been several stories in the news lately about swimmers getting killed by Electrical Shock Drowning (ESD) when swimming near docs in Marinas. The diagram at the following link shows how it happens, but I'm not understanding why electrical service to the docs isn't Ground Fault Circuit...
  45. S

    How can a static shock load requirement be defined?

    A customer of my employer emailed me with some requirements for a new machine that they plan to build. Everything was fine until I got to the part of the static shock load requirement of 2700in-lbs. A static load is a force/load put on for a long period of time, but shock load is a sudden or...
  46. Mike J

    Compare 2 mechanical shock scenarios with different magnitude and time

    For example, How does one compare 100 g's for 6 milliseconds to 45 g's for 11 milliseconds. These are two different shock scenarios with different magnitudes and times, so how can I compare them? If I have something that is shock rated at 100 g's for 6 ms does this imply that it will withstand...
  47. T

    Pressure wave vs. Shock wave in solid body

    Hi everyone, I'm having some difficulty comprehending "normal" transmission of stress/strain through a solid body and "shock" transmission of stress/strain. Imagine I have two bodies, one rigid - the other elastic. If the rigid body is fixed in space, and the elastic body is flying at the...
  48. Iron_Man_123

    Traffic shock wave physics -- please explain

    Homework Statement Homework Equations N/A The Attempt at a Solution I can't even understand the question and what is happening in the situation :(
  49. Priyadarshini

    Heat Shock Proteins & Protein Folding: How HSP Helps

    I was watching a video in which they said that HSP is produced to help proteins fold correctly and to prevent them from tangling up and misfolding. But, if the cell is producing another protein, wouldn't the chances of tangling up and misfolding increase (because now you have one extra protein...
  50. hackhard

    Can Concrete Conduct Enough Electricity for a Shock to Be Felt?

    if i touch the live (single phase) wire , i will get a shock.But current will have to flow through the body , via the floor , walls of the building , and into the Earth . But cement has electric resistance higher than 1gigaohm so rms current = 220 v / impedance impedance > 1 giga ohm so rms...