Question

A police car sounding a siren with a frequency of 1280 Hz is traveling at 110.0 km/s.
a) What frequencies does an observer standing next to the road hear as the car approaches and as it
recedes?

b) What frequencies are heard in a car traveling at 110.0 km/h in the opposite direction before and after
passing the police car?

c) The police car passes a car traveling in the same direction at 90.00 km/h. What two frequencies before
and after overtaking are heard in this car?

Answer 1

@ frequency Speed of of source source fs = 1280 HZ = 110 km/h = 30.56 m/s s 343 (343-30.56) velocity of listener VL=0 Velocity of sound V = 343 m/s linstenen observed beyeney for Gunus) fs as Source approches fr - 4 39.5) 160 approches (FuL = 1405. 18 47) recedes fi = ( Ixtus) is - 63 34 58) 1280 ifi = 1175.28 HZ). Speed & (police com) Source vs allodemolha = 20.50m/s 34373018 fr Cappraches) = ( vs) t = -343-30.56) fe cappraches) = 1280 H3 ) , 343 3437.3018) 6 - NAVLA X1280 fr Crecedey). - Date Ofs 11280 = 1070.5772 (343730-18 - 343-30.B

(fc crecedes) = 10 70.57 H7 c) Fr Coppraches) - Montes Dots ų=90km/ha 25m/s fz Capprocky) ( 2017) X1280 = 1302 8 +74 I fi (appracky) = 13021873 p IV+V fs fr Crecedes) = (vitus)" 1343+27 Lizeo = 1261 Hą 1 Fr (recetes) = 12614) recods Answey Appracy 1175.26 Hz 1405-8143 1070.57 Hz 1280 H3 126102 1302-8 13