Safety razor be a generic category of their own and not a variety of safety razor. The similarities between single-edge cartridge blade razors and the classic injector razor do, however, provide equal justification for treating both categories contiguously. In 1974 Bic introduced the disposable razor. Instead of being a razor with a disposable blade, the entire razor was manufactured to be disposable. Gillette's response was the Good News disposable razor which was launched on the US market in 1976 before the Bic disposable was made available on that market. Shortly thereafter, Gillette modified the Good News construction to add an aloe strip
Mach reflection the shock angle exceeds a certain value, the deflection achievable by a single reflected shock is insufficient to turn the flow back to a direction parallel to the wall and transition to Mach reflection is observed. Mach reflection consists of three shocks, namely the incident shock, the reflected shock and a Mach stem, as well as a slip plane. The point where the three shocks meet is known as the 'triple point' in two dimensions, or a shock-shock in three dimensions. The only type of Mach reflection possible in steady flow is direct-Mach reflection, in which the Mach stem is