1. The problem statement, all variables and given/known data 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 . 2. Relevant equations 3. 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 .