A siren placed at a railway platform is emitt | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) Given,frequency of source,$f_s = 5 	ext{ kHz}$.For the passenger in train $A$,the observed frequency is $f_A = 5.5 	ext{ kHz}$.Using the Doppler

Vedclass · Accepted Answer

$2$

Vedclass · Answer

(B) Given,frequency of source,$f_s = 5 	ext{ kHz}$.For the passenger in train $A$,the observed frequency is $f_A = 5.5 	ext{ kHz}$.Using the Doppler effect formula for an observer moving towards a stationary source: $f_A = f_s \left( \frac{v + v_A}{v} ight)$,where $v$ is the speed of sound.$5.5 = 5 \left( 1 + \frac{v_A}{v} ight) \implies 1.1 = 1 + \frac{v_A}{v} \implies \frac{v_A}{v} = 0.1$  --- $(i)$For the passenger in train $B$,the observed frequency is $f_B = 6 	ext{ kHz}$.Similarly,$f_B = f_s \left( \frac{v + v_B}{v} ight)$.$6 = 5 \left( 1 + \frac{v_B}{v} ight) \implies 1.2 = 1 + \frac{v_B}{v} \implies \frac{v_B}{v} = 0.2$  --- $(ii)$Dividing equation $(ii)$ by equation $(i)$:$\frac{v_B / v}{v_A / v} = \frac{0.2}{0.1} = 2$.Thus,the ratio of the speed of train $B$ to that of train $A$ is $2$.

Similar Questions

$A$ car sounding a horn of frequency $1000 \ Hz$ passes a stationary observer. The ratio of frequencies of the horn noted by the observer before and after passing the car is $11:9$. If the speed of sound is $v$,the speed of the car is:

The frequency of a whistle of an engine is $600 \, Hz$ and it is moving with a speed of $30 \, m/s$ towards a stationary observer. The apparent frequency heard by the observer will be .... $Hz$ (velocity of sound $= 330 \, m/s$).

An observer moves towards a stationary source of sound with a velocity of one-fifth of the velocity of sound. The percentage increase in the apparent frequency is (in $\%$)

An engine giving a whistle is moving towards a stationary observer with a speed of $110\, m/s$. What will be the ratio of the frequency of the whistle heard when the engine is approaching and receding from the observer? (Speed of sound $= 330\, m/s$)

$A$ bus is moving with a velocity of $5 \, ms^{-1}$ towards a huge wall. The driver sounds a horn of frequency $165 \, Hz$. If the speed of sound in air is $335 \, ms^{-1}$, the number of beats heard per second by the passengers in the bus will be:

Vedclass Test Series

Exam Paper Generator

Online Exam Module