KCET 2014 Physics Solved Paper

According to Doppler effect there is a change in frequency or wavelength of a wave in relation to observer who is moving relative to the wave source, which is given as f′=(‌

v

v−vs

)f
where f ′ is the apparent frequency; f is frequency of source; vS is velocity of source; v is velocity of sound
GivenTherefore, Thus, frequency of whistle heard by a stationary observer on the platform is 350 Hz