Two ambulances have identical sirens that emit a rest frequency of 700 Hz
PHYSICS · Single correct · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
Two ambulances have identical sirens that emit a rest frequency of 700 Hz. Ambulance 1 approaches a stationary observer at 10 m/s, while Ambulance 2 approaches from the opposite direction at 15 m/s. Assume the speed of sound in air is 340 m/s. What beat frequency does the observer hear at the instant both sirens are sounded?
(a) 22 Hz
(b) 11 Hz
(c) 0 Hz
(d) 10 Hz