Originally Posted by
Larry Gibson
Lloyd
Yes, Mach I and Mach II are speeds but there is a shock wave that forms as the bullet/aircraft, etc. passes through Mach I. The shock wave changes in force, intensity and location created on the bullet/aircraft, etc. as additional Mach levels are passed. However you hear only one sonic boom, crack or whatever you call it when the shock wave reaches you. The shock wave follows behind and outwardly from the path of the bullet/aircraft, etc. You hear only one "boom/crack" regardless of whether additional Mach levels are reached later because the shock wave/boom is already past you. If it's going Mach I, II or III you will hear only one boom/crack because there is usually only one shock wave created regardless of the mach level or if more they are so close together you can't distinguish between them.
"Either way its irrelevant in bullets because I don't know of a single one of them that does mach 2."
Uh, Lloyd, lots of bullets travel faster than Mach II.......any over 2200 - 2400 fps are traveling Mach II or greater. You only hear one "crack" (if the muzzle blast is suppressed) because if the muzzle velocity is above Mach I, II or III it is already that Mach level speed on exit from the muzzle. There is no "crack" of the bullet while it is still inside the restriction of the barrel reaching whatever Mach level+ it exits the muzzle at.
Since the bullet is at max velocity on muzzle exit it will not increase in velocity and go "through" another Mach level (perhaps this is what you meant?).