Question

A train is moving with a uniform speed of 33 m/s and an observer is approaching the train with the same speed. If the train blows a whistle of frequency 1000 Hz and the velocity of sound is 333 m/s, then the apparent frequency of the sound that the observer hears is:

• A. 1220 Hz
• B. 1099 Hz
• C. 1110 Hz
• D. 1200 Hz

Answer 1

The correct option is A 1220 Hz

Apparent frequency, $\nu =\left(\frac{v+u_0}{v-u_s}\right){\nu }_0=\left(\frac{333+33}{333-33}\right)\times 1000$$=\frac{366}{300}\times 1000=1220Hz$