A train is approaching towards a platform with a speed of 10 m `s^(-1)` while blowing a whistle of frequency 340 Hz. What is the frequency of whistle heard by a stationary observer on the platform ? Given speed of sound `= 340 ms^(-1)`.

Options

A. 330 Hz
B. 350 Hz
C. 340 Hz
D. 360 Hz

Answer

B

Explanation

here v = 340 Hz, `u_(s) = 10 m/s , v = 340 ms^(-1)`
`therefore` Apparent frequency v. = `((v)/(v - u_(s))) v `
= ` ((340)/(340 - 10)) xx 340`
= 350 Hz
so correct choice is b.