A train moving at a constant speed is passing a stationary observer on a platform. a flute player is playing a note with frequency of 940Hz. after the flute has passed, the observer hears the sound frequency of 915Hz. What is the speed of the train? The speed of sound in air is 343m/s.
so
Vs = ((Fs/Fo)-1) * v
is that the correct equation
Vs = ((940/915)-1)*343
Vs = 9.37m/s?
http://formulas.tutorvista.com/physics/doppler-shift-formula.html
Yes, you are on the right track with the formula you have used.
The equation you have used is the correct formula to calculate the speed of the train based on the change in frequency observed by the stationary observer. The formula is:
Vs = ((Fs/Fo) - 1) * v
where:
Vs is the speed of the train relative to the observer,
Fs is the observed frequency of the sound (915 Hz) after the flute has passed,
Fo is the original frequency of the sound (940 Hz) emitted by the flute while passing the observer, and
v is the speed of sound in air (343 m/s).
Plugging in the values, we get:
Vs = ((915/940) - 1) * 343
Vs = (-0.0266) * 343
Vs ≈ -9.15 m/s
However, it is important to note that the negative sign indicates that the train is moving in the opposite direction of the sound source (towards the observer). Therefore, we can take the absolute value of the speed to determine the magnitude of the train's speed.
So, the speed of the train is approximately 9.15 m/s.