Question

A source of sounds is travelling with a velocity of 40 km/hr towards an observer and emits sound of frequency 2000 Hz. If the velocity of sound is 1220 km/hr, then what is the apparent frequency heard by the observer? 

(a) 2068 Hz 

(b) 2180 Hz 

(c) 2000 Hz

(d) 1980 Hz

Answer 1

Correct answer is (a) 2068 Hz

\(f' = (\frac{v}{v-v_s}) \times f\) = \(\frac{1220}{1220 - 40} \times 2000 = 2068 Hz\)