EAMCET Engineering 2009 Solved Paper

Listener go from A→B with velocity (u) let the apparent frequency of sound from source A by listener‌n′=n(‌

v−vo

v+vs

)
or ‌n′=680(‌

340−u

340+0

)
The apparent frequency of sound from source B by listener
n′′‌=n(‌

v+vo

v−vs

)
‌=680(‌

340+u

340−0

)
But listener hear 10 beats per second.
Hence, ‌‌n′′−n′=10
or 680(‌

340+u

340

)−680(‌

340−u

340

)=10
or 2(340+u−340+u)=10
or u=2.5m s−1