A train, standing in a station yard, blows a whistle of frequency 400Hz in still air. The wind starts blowing in the direction from the yard to the station with a speed of 10m//s. Given that the speed sound in still air is `34om//s,

Options

A. `a,b` are true
B. `b,c` are true
C. only `c` true
D. `a,b,d` are true

Answer

A

Explanation

`V=V+V_(w)=340+10=350m//s`
`f^(1)=g((V+V_(w)-0)/(V+V_(w)-0))=f`