Numerical Problem 9, Waves, Physics 11 … msa admin January 18, 2021 A sound source vibrates at 200 Hz and is receding from a stationary observer at 18 m/s. If the speed of sound is 331 m/s what frequency does the observer hear? 4 Comments A sound source vibrates at 200 Hz and is receding from a stationary observer at 18 m/s. If the speed of sound is 331 m/s…