May 12, 2013

Supersonic aircraft

The speed of sound, or sonic speed, is called Mach 1. It varies with the pressure and temperature of the air, but is about 720 miles per hour (1,200 km/h). Something that travels faster than sound is known as supersonic. Twice the speed of sound is Mach 2, and so on. Some planes can reach Mach 3 or more. The first person to fly faster than the speed of sound was Captain Charles "Chuck" Yaeger in a rocket plane, the Bell X-1. It blasted through the sound barrier in 1947. Supersonic aircraft overtake their own sound, which spreads out behind them in a shock wave that we hear on the ground as a sonic boom. (‘World of Science’)