98.18: When a train is at rest, )u6ih 2h;)x3 u7qs4 pugirlh(fdm 6stboth 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 frequency of _____ Hz and the ticket seller hearsu6 ifh)7qhupmxtiu3s;4() hdrls g 26 a frequency of ____ Hz.

  08.18: A car is moving to the left at 20 m/s while a truck is moving to the rn4i-zsqa eznv).l2 q6 . qtfy5ight at 25 m/s. If the truck emits a sound of frequency 5000 Hz, what is the perceived frequency of the s av4fqt 6.i) .z5enlszqny-q2ound 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 travels along tq d xnyk p9f92o-2d.nr;kkt1ihe 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 )ch8embp j4;ul,p bt*crash test at 30 m/s. The horn is emitp,) l84*ucbtm;ejpb hting 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 the driver of the car detect?