Have you ever heard a loud sound like an explosion when a fast airplane was flying overhead? This sound is produced by a plane as it passes the sound barrier. Now what is this sound barrier and why does the plane produce this Boom?

Sound, as you know, travels at a certain speed. The speed depends on the altitude. At sea level, the speed of sound is about 760 miles (1,220 kilometers) per hour, and at a height of 11,000 meters, it’s 660 miles (1,060 kilometers per hour. When a plane flies at speeds close to the speed of sound, it undergoes certain kinds of stress. When it is flying at ordinary (slower) speeds, the forward part of the plane sends out a pressure wave. This wave travels at the speed of sound.