Question:

Example 8.7: A bat, flying at velocity Vᴮ = 12.5 m/s, is followed by a car running at velocity Vᴮ= 50 m/s. Actual directions of the velocities of the car and the bat are as shown in the figure below, both being in the same horizontal plane (the plane of the figure). To detect the car, the bat radiates ultrasonic waves of frequency 36 kHz. Speed of sound at surrounding temperature is 350 m/s. There is an ultrasonic frequency detector fitted in the car. Calculate the frequency recorded by this detector. The ultrasonic waves radiated by the bat are reflected by the car. The bat detects these waves and from the detected frequency, it knows about the speed of the car. Calculate the frequency to the reflected waves as detected by the bat. (sin 37° = cos 53° = 0.6, sin 53° = cos 37° = 0.8)