Answer:
[tex]f_o=592.36 Hz[/tex]
Explanation:
Given that
Train 1 (observer):
Speed = 109 km/h
Train 2 (source):
Speed = 99 km/h
Train 2 emitting frequency = 500 Hz
We know that observer and source are moving toward each other, then frequency heard by observer can be given as follows
[tex]f_o=\left(\dfrac{C+V_o}{C-V_s}\right)f_s[/tex]
Where C is the velocity of sound (C=1225 Km/h)
Now by putting the values
[tex]f_o=\left(\dfrac{C+V_o}{C-V_s}\right)f_s[/tex]
[tex]f_o=\left(\dfrac{1225+109}{1225-99}\right)\times 500[/tex]
[tex]f_o=592.36 Hz[/tex]