1. A submarine travelling at a speed of 10ms -1 “pings” an underwater sonar detector which is directly inline with the submarine. The broadcast frequency of the submarine is 1100Hz and the detected frequency is 1107Hz a) Is the submarine moving towards or away from the sonar detector? b) What is the speed of the sound waves in water? Do now: Rātapu, 17 Haratua 2015

2. A fire engine travelling at a speed of 40.0 ms -1 sounds a siren of frequency 500 Hz. The speed of sound is 330 ms -1. In the back of your books, sketch a graph of the frequency observed versus distance between observer and fire engine “Indirect” Doppler