98.18: When a train is /ux ( mod00rxpat rest, both a passenger on the train and a ticket seller on the station agree that theo 0xmpx0/(dur 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 tov5p 1r0xd5 h3kd 8yhmte -nh0v the left at 20 m/s while a truck is moving to the right at 25 m/s. If the truck emits a soundnv8 0yhrkd5p51-ehmh0 vdx t3 of frequency 5000 Hz, what 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 sourcuemz )8f slp/b(h,w dme-p ht5n dm8/8e travels 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 towaysvo7l8 kh . e )0 ss)u3 rhojpcho*(bb6l2ka)rd a brick 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 sto()o b b.8 l02ys hs7ps)el3kvahku6)*hro jcill and the speed of sound in air is 340 m/s, what beat frequency from the horn would the driver of the car detect?