As a train moves away from you, the frequency of its whistle is determined to be 475Hz. If the actual frequency was 500 Hz and the speed of sound in air is 350m/s, what is the Train's speed?

answer is 18.4m/s please show and explain steps

2 answers

There is a standard formula for this

In classical physics, where the speeds of source and the receiver relative to the medium are lower than the velocity of waves in the medium, the relationship between observed frequency f and emitted frequency f_\text{0} is given by:[5]

f = (v+vr)fo/(v+vs)

where

v is the velocity of waves in the medium;
vr, is the velocity of the receiver relative to the medium; positive if the receiver is moving towards the source (and negative in the other direction);
vs, is the velocity of the source relative to the medium; positive if the source is moving away from the receiver (and negative in the other direction).

The frequency is decreased if either is moving away from the other.
please answer it