98.18: When a train is a7ay3k (5 nxgnrt rest, both a passenger on the train and a ticket seller on the station agree 7 rakg3xn(5yn 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 frequency of _____ Hz and the ticket seller hears a frequency of ____ Hz.

  08.18: A car is moving to the left at 20 m/s otzzdp c-f.56haw 2ka* .ma,p while a truck is moving to the right at 25 m/s. If the truck emits a sound of frequency 5000 Hz, what is the perceived frequency of the sound by the driver of the car? Assume the vehicles are movih,t* zmfc 2a.d.aw app6-5zokng directly away from each other on a $20.0^{\circ}C$ day

  17.39: A point wave source travels al ll.b:q+ljsx3c;nala4 .x s+ gong 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 brick wall1 ywq9) emhlp+.vi5 ll in a crash test at 30 m/s. The horn is emitting a sound with frequency 250 Hz as it app.+ veyli )5lhp 1qwlm9roaches 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 the driver of the car detect?