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. S

    Super quick easy question about spinal shock?

    During spinal shock, are all spinal reflexes gone, or only reflexes below the lesion. Thanks :smile:
  2. Terocamo

    Why do we need an Earth wire in our appliances?

    I was reading about current electricity and some how I came across the idea that a circuit of no earthed point will not cause any electric shock. I wonder if it is right cause if it is, why do we need an Earth wire in our appliance. I am also suspicious because if the circuit is not earthed...
  3. W

    Can mechanical shock enhance the flux through a magnetic circuit?

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  4. W

    Amount of current and voltage in an average shock from a door nob?

    Amount of current and voltage in an average "shock" from a door nob? What is the amount of current and voltage in an average "shock" from a door nob/handle? I have looked everywhere and cannot seem to find it! Please help! Thanks
  5. S

    Why does the heart lose its sympathetic supply when C7 is transected?

    Hello everyone, Quick question about spinal cord shock. 1. If C7 is transected, why does heart lose its sympathetic supply. I don't know much about autonomic nervous system, but isn't it coming from sympathetic trunk located outside the spinal cord, so how can it have an effect. 2. Also...
  6. D

    Multiple Shock reflection problem

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  7. S

    Modelling simulation for 6g shock

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  8. B

    Calculating G-Shock of Dropping 5kg Box from 20m

    If I drop a box of the side of a building (20m) that is 5kg, what is the G shock that this will experience? F=mg is the force, obviously. Based on basics, I'm coming up with 1G, but that doesn't make sense - the shock is going to be bigger based on the height. Say I determine the energy...
  9. B

    The effects of electrical shock on the brain from non-localized contact area

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  10. S

    Wire Cable Shock Load Calculation

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  11. S

    Medical What is the voltage and force of the shock

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  12. N

    Electric Safety: Protect Yourself from Electrical Shock

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  13. L

    Shock solution using conservation law

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  14. L

    Shock solution by conservation law

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  15. F

    Oblique Shock Angle Calculation

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  16. R

    Is the Red Dashed Shock Present at Freestream M=2?

    At freestream M=2 will the red dashed shock exist? I know there is a shock wave on the bottom.
  17. S

    Is High Voltage DC Current Dangerous?

    I have heard that 'we don't get shock from dc current because it is constant but we get shock from ac current because it is alternating'.Is that true? If it is HIGH VOLTAGE DC CURRENT THEN?
  18. T

    What are the different materials used in a spring shock absorber?

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  19. P

    How does the shock detection switch work in the ASLS15 model?

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  20. Loren Booda

    Protect Your Electronics: Choosing the Right Surge Protector for Thunderstorms

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  21. A

    Oblique shock reflection on solid boundary

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  22. N

    Industrial scientific culture shock?

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  23. J

    Shock waves in crystals - temperature effect

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  24. M

    Oblique + Normal Compression shock and nose cone angles

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  25. J

    Shock absorber/Suspension advice (bike project)

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  26. H

    What is the most affordable and flexible foam for shock absorption?

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  27. J

    Uncovering the Truth Behind CCHR: Shock & Awe

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  28. S

    Understanding Shock Sensor G-Force Ranges & Outputs

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  29. E

    Electric Shock Effects: Current vs. Power

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  30. H

    Bicycle Rear Shock damping coefficent

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  31. S

    Stagnation pressure for attached shock

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  32. 0

    Motion problem - Shock drop ride

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  33. B

    Spherical shock wave propagation in liquids

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  34. Borek

    What happened to my old friend's son?

    I am in shock :( Sorry, I have to write about it. I had a close friend 25 years ago, we studied chemistry together. Somehow we haven't seen each other since then, just now and then exchanged messages/informations through mutual friends. I have just learned that two days ago his 18 yo son...
  35. O

    J shock in a gas for gamma = 7/5

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  36. G

    Traffic Shock Wave - Speed & Direction of Wave

    An abrupt slowdown in concentrated traffic can be travel as a pulse, termed a shock wave, along the line of cars, either downstream (in the traffic direction) or upstream, or it can be stationary. Figure below shows a uniform spaced line of car moving at speed v = 25.0 m/s toward a uniformly...
  37. Y

    Bicycle Shock Absorber Question

    I have a mountain bicycle with a rear spring shock absorber. Recently the shock absorber broke. Until I can purcahse a replacement I was thinking of building a rigid piece of steel to replace the shock, essentially making my bike a non-suspended unit, but still be able to ride it. So here...
  38. S

    Mechanical vibration and shock control

    Please could anyone help me on the topic "Controlling the vibration and shocks received by elctronic-mechanical components"?
  39. R

    Supersonic Jet: Mach 3 at Altitude 20,000m - Shock Wave & Boom Times

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  40. B

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    I've done searching on the topic, and I really don't know where else to turn, so here it goes. I hope somebody can point me in the right direction. I've been working on using a shooting method to solve the steady-state spherically symmetric fluid equations for an accreting plasma. Basically, it...
  41. mtworkowski@o

    Are Shock Absorbers the Unsung Heroes of Car Performance?

    I'd like to open a discussion on the ins and outs of shock absorbers on cars. The ability of a device to restrict the extension of the suspension springs works miracles that are not always appreciated.
  42. G

    Electric Eel: Why It Doesn't Shock Itself

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  43. H

    Shock waev? Isentropic reduction of velocity?

    Hi all. We are to compare the effect of a shock wave, that is the irreversibilities associated. We have comptued that the upstream and downstream velocities of a shock wave are 1029 m/s and 266.8 m/s respectively. The upstream pressure and temperature is 105kPa and 290K. What question...
  44. N

    How to Calculate Shock Wave Cone Angle and Plane Speed in a Sonic Boom Situation

    Homework Statement You look directly overhead and see a plane exactly 1.4·km above the ground, flying faster than the speed of sound. By the time you hear the sonic boom, the plane has traveled a horizontal distance of 2.4·km. (a) Find the angle of the shock wave cone. (b) Find the...
  45. E

    More likely to get a shock on a dry day?

    Why are we more likely to get a shock on a dry day than on a rainy day?
  46. S

    Superbubbles from shock waves from supernova or stellar winds?

    Can someone explain to me how shock waves from supernova or stellar winds can generate a superbubble? Does the energy from the shock get converted to thermal energy through compression?
  47. P

    Why the Neutral Wire Causes No Electric Shock

    Why the neutral wire (the cold) does not cause an electric shock?
  48. P

    Physics Help: Calculating Electric Shock Voltage/Current

    Physics help, urgent! Homework Statement The damage caused by electric shock depends on the current fowing through the body; 1 mA can be felt and 5 mA is painful. Above 15 mA, a person loses muscle control, and 70 mA can be fatal. A person with dry skin has a resistance from one arm...
  49. W

    3 spring shock absorber help

    Homework Statement The problem verbatim from the text: "One of the winners in an egg-drop contest was a structure in which rubber bands held the egg at the center of it. Attached is a model. Consider the egg to be a particle of mass m and the springs to be linear with spring constants k...
  50. Z

    How does the V shape of a shock wave depend on the speed of the wave source?

    Hello, the question I have to answer is above in the Title...I thought that the V shape of the shock wave gets wider the faster you are going. No? Thanks Zach
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