98.18: When a train is at rest, both a passenger on the train a: toaq,(9eel and a ticket seller on the station agree thatto:al( , 9eqea 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 while a truck is moving to y.wyu40.t8 vvh :m*7dof sa o;1dr dzethe 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? Assum*vwra 1 4e7udzy.s8:odhtdom vfy0 .;e the vehicles are moving directly away from each other on a $20.0^{\circ}C$ day

  17.39: A point wave swp ruxg7ca2 z)(la *c)w,l*jmource 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 toward a brick wall in a crash test at 30 rn96xb(km99kya 1ngmm/s. The horn is emitting a sound with frequency 250 Hz as it approaches the walkk9(n9arx1 96nygbmm l. 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?