Mach number a small area around the object's leading edge. (Fig.1b) Fig. 1. "Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)." When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this.
David Mach David Mach David Mach (born 18 March 1956) is a Scottish sculptor and installation artist. Mach was born in Methil, Fife. His artistic style is based on flowing assemblages of mass-produced objects. Typically these include magazines,vicious teddy bears,newspapers, car tyres, match sticks and coat hangers. Many of his installations are temporary and constructed in public spaces. One example of his early magazine pieces, "Adding Fuel to the Fire", was an installation assembled from an old truck and several cars surrounded and subsumed by about 100 tons of magazines, individually arranged to create the impression that the vehicles were being caught