Two trains are moving towards each other with speeds of 20 m/s and 15 m/s relative to the ground. The first train sounds whistle of frequency 600 Hz, the frequency of the whistle heard by a passenger in the second train before the meets is (the speed of sound in air is 340 m/s)

Question

Dr. Abubacker · Accepted Answer

(d) The perceived frequency $\left( f^{'} ight)$ is related to the actual frequency $\left( f_{o} ight)$ and the relative speeds of the source $\left( v_{s} ight)$ and observer $\left( v_{o} ight)$ of waves in the medium is given by
$f^{'} = f_{o}\left( \frac{v + v_{o}}{v - v_{s}} ight)$
Given,
v=340m/s $v_{o} = 15$m/s, $v_{s} = 20$m/s
$	herefore f^{'} = 600 	imes \left( \frac{340 + 15}{340 - 20} ight)$
$= \frac{355}{320} 	imes 600 = 666Hz$

Q. Two trains are moving towards each other with speeds of 20 m/s and 15 m/s relative to the ground. The first train sounds whistle of frequency 600 Hz, the frequency of the whistle heard by a passenger in the second train before the meets is (the speed of sound in air is 340 m/s)

Explanation

Reviewed by Dr. Abubacker

Want more practice?