In case 1, a source of sound approaches a stationary observer at speed u. In case 2, the observer moves toward the stationary source at the same speed u. If the source is always producing the same frequency sound, will the observer hear the same frequency in both cases, since the relative speed is the same each time? Why or why not?

Police car with siren travelling v = 28m/s with siren frequency = 436 hz. Speed of sound is 343m/s. What is the freq in hz that an observer hears as car moves away?

Early Doppler shift experiments were conducted using a band playing music on a train. A trumpet player on a moving railroad flatcar plays a 320-Hz note. The sound waves heard by a stationary observer on a train platform hears a frequency of 350 Hz. What is the flatcar’s speed in mph? The temperature of the air is TC = 22°C .

There are two trains (A and B) each with the same whistle that produces a sound wave at 403 Hz. Train A is at the origin and is stationary. An observer is to the right of train A and is moving to the right, away from train A, at 20 m/s. Train B is to the right of the observer and train A. It is moving to the right at 35 m/s, away from both the observer and train A. The temperature is 20 degrees C. What is the beat frequency between whistles A and B as heard by the observer?