Two trains are travelling towards each other both at a speed of `90 km h^-1`. If one of the trains sounds a whistle at 500 Hz, what will be the apparent frequency heard in the other train ? Speed of sound in air `= 350 m s^-1.

Explanation

According to the given data,
`V_s=90 km/hour=25 m/sec`
`v_0=25m/sec`
so Apparent frequency heard by the observer in train B
`((350+25/(350-25))xx500=577Hz`