I was watching this high speed video and they showed a shockwave that was faster than the speed of sound they saw in the object. How is that possible? Isn't the speed of sound the fastest something propagates as sound is a pressure wave?
pull down to refresh
0 sats \ 3 replies \ @k00b 1 Oct
Sound travels at different speeds in different materials. It travels at one speed in air, at another speed in water, etc. Even in air, the speed of sound depends on conditions like temperature, humidity, etc.
The same is true for the speed of light. It travels slower in air and glass than in a vacuum.
reply
0 sats \ 2 replies \ @carter OP 1 Oct
but isnt the shockwave traveling at the speed of sound when its cracking? so how is there a faster speed of sound? Like I would expect the 1st shockwave propagating to be the speed of sound in the material but this seemed like there was 2. 1 faster like transverse wave and then a slower one that went at the calculated speed of sound
reply
0 sats \ 1 reply \ @k00b 1 Oct
I see that's interesting. Basically the question is whether damage can be done faster than sound travels through a material? That violates my intuition too. I haven't watched the video yet.
reply
0 sats \ 0 replies \ @adlai 3 Oct
100%
sound is the adiabatic aka isentropic [ read, "reversible" ] news about the damage done by consecutive collisions that occur more densely than the material dissipates the news.
here's a similar situation that might give you a general intuition for how the idealised acoustic wave gets disrupted by supersonic displacement:
imagine you're sitting at the stern of a boat, watching the wake propagate; if you look aft, you'll see the nice idealized 45-degree wake and it'll appear to be two lines as you watch the distant edges. this surface wave is the two-dimensional analogy of a sonic boom, and if you toss pebbles into the space within the wake, you can see surface ripples which are directly analogous to regular sound waves. now get on waterskis behind the boat, and look towards it with the wake spreading around you, and watch what happens as the boat's speed increases: the wake's idealized shape doesn't change, although it becomes more dramatic, because the submerged portion of the hull must push aside a larger volume of water per unit time (take this to an extreme, and you get hydroplaning....)
reply