A boy riding on his bike is going towards east at a speed of  42 m/s. At a certain point, he produces a sound pulse of frequency 1650 Hz that travels in air at a speed of 334 m/s . A second boy stands on the ground  450 south of east from him. The frequency of the pulse as received by the second boy is (in Hz)

1. Speed of boy  v=42 m/sFrequency of sound pulse  v0=1650 HzB1 or the first boy is the source of the sound and  B2 is the listener. vs  is the component of the velocity of the source along the source – listener axis (SL axis). Here,vs=42cos450=4 m/s  Using Doppler’s effect formula  v=v−vLv−vAv0Speed of sound in airv=334 m/s, vs=4 m/s, vL=0 v=334334−4×1650 Hz=334330×1650 Hz=1670 HzTherefore, the correct answer is 1670.00