Machmachthe ratio of the speed of a moving object to the speed of sound in the medium surrounding it, usually followed by a number to indicate how many times faster than the speed of sound it moves It was in honour of Mach's work on shock waves associated with projectiles moving through the air that the Mach numbers of speed were named after him; a speed of Mach 1 is equal to the speed of sound, Mach 2 twice the speed of sound, and so on. In addition to these, we also have one supersonic wind tunnel capable of air velocities up to Mach 4. The height for our flight home would be 26,000 ft, with the speed once again at mach 0.8 (600 mph).