45 2) A policeman is waiting along a highway for speeders; the speed of MPH approaching cars is measured with an ultrasonic device that emits sound waves with a frequency of 39.6 kHz. A car is approaching him at a constant speed of 35.0m/s. The wave is reflected by the car and interferes with the emitted sound producing beats. The temperature is 20 C. (a) (3pt) If the driver of the car measures a frequency of 43.64kHz, how fast is the car traveling towards the policeman? (b) (3pts) What is the frequency of the reflected sound waves measured by the stationary policeman? (c) (3pt) What is the resulting beat frequency created by the interference of the original and reflected sound waves? (d) (1pt) Are any of these sound waves audible to humans