CGPET 2018 Solved Paper

Given, in this condition, v0=vs=15m∕s
Virtual frequency of sound source moving towards a huge wall,
n′=(

v

v−vs

)n .......(i)
The frequency of echo heard by driver,
n"=(

v+v0

v

)n′
From Eqs. (i) and (ii), we get
n"=(

v+v0

v−vs

)n
=(

340+15

340−15

)×1000
≈1092Hz