question_answer

Two engines pass each other moving in opposite directions with uniform speed of 30m/s. One of them is blowing a whistle of frequency 540 Hz. Calculate the frequency heard by driver of second engine before pass each other. Speed sound is 330 m/sec.   JEE Main Online Paper (Held On 09 April 2016)

A) 540 Hz                  

B) 648 Hz

C) 270 Hz                  

D) 450 Hz

Correct Answer: B

Solution :

\[{{f}_{0}}=\left( \frac{330+30}{330-30} \right)540=648Hz\]