Question

A train approaching at the railway crossing at a speed of 120 km/h sounds a whistle at frequency 640 hz when it is 300m away from the crossing. The speed of sound in air is 340 m/s. What will be the frequency heard by a person standing on a road perpendicular to the track through the crossing at a distance of 400 m

Answer 1

Answer:

From the geometry of the figure cosθ = 3