Sonic Boom-THE HINDU-22-05-2020.

Details:
When an aircraft travels at supersonic speed – meaning faster than sound – the field of sound waves moves to the rear of the craft. A stationary observer hears no sound when a supersonic flight approaches, since the sound waves are at the rear of the latter. The ‘loud sound’ heard in Bengaluru on Wednesday afternoon, which puzzled lakhs of city dwellers, was revealed to have emanated from an IAF test flight involving a supersonic profile.

In a statement, the Ministry of Defence's PRO in Bengaluru said, “The sonic boom was probably heard while the aircraft was decelerating from supersonic to subsonic speed between 36,000 and 40000 feet altitude.

” It confirmed that the aircraft belonged to the Aircraft Systems and Testing Establishment and had flown in allocated airspace outside city limits.

What is a ‘sonic boom’?

From a stationary source, such as a television set, sound waves travel outwards in concentric spheres of growing radii.

Coronavirus Explained:

When an aircraft travels at supersonic speed – meaning faster than sound – the field of sound waves moves to the rear of the craft. A stationary observer thus hears no sound when a supersonic flight approaches, since the sound waves are at the rear of the latter.

At such speeds, both newly created as well as old waves, are forced into a region at the aircraft’s rear called a ‘Mach cone’, which extends from the craft and intercepts the Earth in a hyperbola-shaped curve, and leaves a trail called the ‘boom carpet’. When such aircraft fly at a low altitude, the sonic boom can become intense enough to cause glass to crack or cause health hazards.

Overland supersonic flights have thus been banned in many countries.

Supersonic flights:

In 1947, the American military pilot Chuck Yeager became the first to breach the sound barrier, flying the Bell X-1 aircraft at 1127 kmph. Since then, many supersonic flights have followed, with advanced designs allowing speeds of over Mach 3, or three times the speed of sound.