Question

A rocket is moving at a speed of $200{ms}^{-1}$ towards a stationary target. While moving, it emits a wave of frequency $1000Hz$. Calculate the frequency of the sound as detected by the target. (Velocity of sound in air is $330{ms}^{-1}$)

Answer 1

Speed of rocket (source) $v_s=200m/s$

Speed of sound in air $v_{sound}=330m/s$

Original frequency of sound $f_o=1000Hz$

Apparent frequency of sound heard by the stationary target, $f^{\prime }=f_o[\frac{v_{sound}}{v_{sound}-v_s}]$

$\therefore$ $f^{\prime }=1000[\frac{330}{330-200}]=2538.5Hz$