Question

when does a supersonic aircraft make a sonic boom?
multiple choice
when it crosses the sound barrier from either direction
only when it goes faster than the speed of sound
at all times when it is flying at the speed of sound or faster
only when it breaks the sound barrier

Explanation:

A sonic boom occurs when an aircraft is flying at or above the speed of sound. The pressure - waves from the aircraft cannot escape forward and build up, creating a shock - wave. This shock - wave results in the sonic boom. It is not just when breaking the sound barrier (as it can also occur when flying continuously at supersonic speeds) or only when going faster (it can occur at the speed of sound too). Also, it's not just when crossing from either direction (the key is the speed relative to the speed of sound).

Answer:

at all times when it is flying at the speed of sound or faster