mach's picture of a bullet the article now says the first to discover this shock was ernst mach in his original picture showing a bullet in a supersonic flow that cause the oblique shock is this talking about this picture i think this is a picture of a bullet fired into stationary air while the sentence above seems to say that it's being fired into air that was already moving at supersonic speeds i suggest discussing this at talk shock wave mach's picture of a bullet since there is already discussion there although i suspect a change in wording in this article is required