98.18: When a train is at resj 4 gimw ) o.a5f8:ta(1to;2ebmey llrt, both a passenger on the train and a ticket seller on the station agree that the trains whistle produces sound at a frequency of 120 Hz. When the train is moving away from the station at 15 m/s, the passenger hears a frequency4 e 5b(m21armll.tie yo)o: gtwf j8a; of _____ Hz and the ticket seller hears a frequency of ____ Hz.

  08.18: A car is moving to the left at 20 m/s whiled be0m3-f;c zqunj5q 7 a truck is moving to the right at 25 m/s. If the truck emits a sound of frequency 5000 Hz, whac;dzu je n3qf57 m0q-bt is the perceived frequency of the sound by the driver of the car? Assume the vehicles are moving directly away from each other on a $20.0^{\circ}C$ day

  17.39: A point wave source travehb2k9 thoo vu84+77awd zpk d;ls along the x-axis at constant speed $v_s$. Stationary observers on the x-axis measure the wavelength of the waves that they receive. The ratio of the wavelength measured at a location behind the source to the wavelength measured at a location in front of the source is 1.50. If the wave speed is v, what is the source speed $v_s$?

  02.47: A car heads toward a briv9.q jyb;v ml1ck wall in a crash test at 30 m/s. The horn is emitting a sound with frequency 250 Hz as it approaches the wall. If the air is still and the speed of sound in air is 340 m/s, what beat frequency from the horn would thjyq;m9. vl1v be driver of the car detect?