When a helicopter is hovering 1450 m directly overhead, an observer on the ground
measures a sound intensity I. Assume that sound is radiated uniformly from the helicopter and that ground reflections are negligible. How far must the helicopter fly in a straight line parallel to the ground before the observer measures a sound intensity of ¼ I ?
It measures the sound intensity from the helicopter on the ground. The solution is detailed and has a '5/5' rating.