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Solution: An acoustic burglar alarm consists of a source emitting waves of frequency 28.50 kHz. An intruder is walking at an average speed of 0.9600 m/s directly away from the alarm. Take the speed of sound to be 343.0 m/s.(a) What is the wave length of the source waves?(b) What is the frequency and wavelength for the intruder? The waves are reflected by the intruder and back to the alarm system.(c) What is the frequency and wavelength for the waves reflected from the intruder, as detected at the source?(d) What is the beat frequency between the source waves and the waves reflected from the intruder?

Problem

An acoustic burglar alarm consists of a source emitting waves of frequency 28.50 kHz. An intruder is walking at an average speed of 0.9600 m/s directly away from the alarm. Take the speed of sound to be 343.0 m/s.

(a) What is the wave length of the source waves?

(b) What is the frequency and wavelength for the intruder? The waves are reflected by the intruder and back to the alarm system.

(c) What is the frequency and wavelength for the waves reflected from the intruder, as detected at the source?

(d) What is the beat frequency between the source waves and the waves reflected from the intruder?