Two speakers, A and B, are moving towards each other with a closing speed of 30 m/s, meaning the distance separating the two speakers is decreasing by 30 m every second. At rest, speaker A emits a frequency of 150 Hz and speaker B emits a frequency of 200 Hz. For all questions, assume the speed of sound is 340 m/s.
(a) From speaker A's perspective, what is the frequency of speaker B?
(b) From speaker B's perspective, what is the frequency of speaker A?
(c) If an observer were standing in between the two speakers, and speaker A were moving towards him with a speed of 10 m/s, what beat frequency would the observer hear?