Submarine A, with velocity 21 m/sec, receives from directly behind it, the sound with frequency 266 cy/sec, from submarine B which is known to emit sound at 265 cy/sec.
The two submarines are 1800 meters apart. Speed of sound in sea water 1450 m/sec.
If the two subs maintain courses and speeds, will there be a collision, and if so, in how many seconds?
Recall that the Doppler equation is:
(1) f' = f (v + vs) / (v - vo) in which:
f = frequency emitted by source
f' = frequency received by observer
v = velocity of sound
vo = velocity of observer (+ if toward source, - if away from source)
vs = ...
With good explanations and four separate steps, the problem is solved.