## Homework Statement

a train moves with uniform velocity . its horn is with a definite frequency . then if the frequency that a man in the station had heard is changed from 5400 Hz to 4500 Hz . calculate :-
1- velocity of train.
2- the real frequency of the source .
let the velocity of sound in air = 330 m/s .

## The Attempt at a Solution

f'/f = v/(v+vs)
vs = velocity of train = 63 m/s .
is that solution is true ?
and i can't solve or understand the second item of my problem .
please i want a help .