Train Horn (1 000 Hz) Approaching at 50 m/s
A train horn sounding at 1 000 Hz and moving at 50 m/s is heard at about 1 171 Hz by a stationary trackside observer.
How to use this tool
- Enter source frequency fā, source velocity vā, observer velocity vā and wave speed v in the fields above.
- Results update instantly as you type ā or click Calculate.
- Read your observed frequency and the full breakdown beneath it.
Trains travelling at 180 km/h create a dramatic Doppler shift ā the horn is roughly a minor third higher in pitch when approaching.
Frequently asked questions
- What is the speed of sound used here?
- 343 m/s at 20 Ā°C in air at sea level. It varies with temperature: roughly v ā 331 + 0.6ĆT(Ā°C) m/s.
- Does the Doppler effect apply to light too?
- Yes, but the relativistic formula must be used. The astronomical redshift of distant galaxies is a Doppler-related phenomenon.