A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz.A car is approaching him at a speed of 33.0 m/s.The wave is reflected by the car and interferes with the emitted sound producing beats.What is the frequency of the beats? The speed of sound in air is .
A) 9.2 kHz
B) 4.1 kHz
C) 4.6 kHz
D) 1.2 kHz
E) 8.2 kHz

Question

A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz.A car is approaching him at a speed of 33.0 m/s.The wave is reflected by the car and interferes with the emitted sound producing beats.What is the frequency of the beats? The speed of sound in air is  .
A) 9.2 kHz 
B) 4.1 kHz 
C) 4.6 kHz 
D) 1.2 kHz 
E) 8.2 kHz

Quizplus · Accepted Answer

The Answer of A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz.A car is approaching him at a speed of 33.0 m/s.The wave is reflected by the car and interferes with the emitted sound producing beats.What is the frequency of the beats? The speed of sound in air is  .
A) 9.2 kHz 
B) 4.1 kHz 
C) 4.6 kHz 
D) 1.2 kHz 
E) 8.2 kHz

A Policeman in a Stationary Car Measures the Speed of Approaching