

Well it isn’t like Japan is invading China. Seems like they just want to make it clear they will in fact respond if China tries something with Taiwan. Japan doesn’t have to beat China, they just have to make it not worth it. And they’d have Taiwan and hopefully the US supporting them in that effort.











It seems that depending on the type of glass and the direction of the waves (longitudinal, shear, or Extensional) the speed of sound in glass can be between 2300-6000 m/s
Longitudinal is the type we normally think of though, and that is between 3900-5600 m/s. Which is still much more variation than I was expecting.
The speed of sound in air is around 340 m/s depending on temperature.
So if the op is correct about the speed, then it seems the cracks propagate slower than the speed of sound in glass.
https://www.engineeringtoolbox.com/sound-speed-solids-d_713.html