1. The problem statement, all variables and given/known data At an air show, a fighter jet does manuevers past the crowd. Your increible hearing notes that the frequnecy of the sound coming from the jet engine drops exactly by one octave when it is approaching you to when it is directely above you (not moving relitive to you). How fast is the jet flying? 2. Relevant equations Mach #= velocity/velocity sound ƒobs=ƒo(v+-d/v+-s) where ƒo= frequency original, d= velocity of detector, s= velocity of source and v is the velocity of sound. 3. The attempt at a solution Since a drop by one octave is the same as half the frequency, we can represent the frequency observed when the plane approaches as ƒ and the frequency heard directly above as f/2. we can then make two equations; Approaching--- ƒ=ƒo(v/v-s) Directly above--- ƒ/2=ƒo(v/v) (no s since its not moving relative to you at that exact moment) However there are still more variables then equation, not sure how to go on from here.