A stationary sound source S of frequency 334 | vedclass

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

Question

(D) The problem involves two steps of the Doppler effect.Step $1$: The reflecting surface acts as an observer moving away from the source $S$. The fre

Vedclass · Accepted Answer

$330$

Vedclass · Answer

(D) The problem involves two steps of the Doppler effect.Step $1$: The reflecting surface acts as an observer moving away from the source $S$. The frequency $f'$ received by the surface is given by $f' = f \left( \frac{V - u}{V} ight)$,where $f = 334 \, Hz$,$V = 330 \, m/s$,and $u = 2 \, m/s$.$f' = 334 \left( \frac{330 - 2}{330} ight) = 334 \left( \frac{328}{330} ight) \approx 331.97 \, Hz$.Step $2$: The reflecting surface now acts as a moving source reflecting the sound back to the stationary observer $O$. The frequency $f''$ heard by the observer is $f'' = f' \left( \frac{V}{V + u} ight)$.$f'' = 334 \left( \frac{328}{330} ight) 	imes \left( \frac{330}{330 + 2} ight) = 334 \left( \frac{328}{332} ight) = 334 	imes 0.98795 \approx 330 \, Hz$.

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:

$A$ motor car blowing a horn of frequency $124\,vib/sec$ moves with a velocity $72\,km/hr$ towards a tall wall. The frequency of the reflected sound heard by the driver will be .... $vib/sec$ (velocity of sound in air is $330\,m/s$).

Two sources $A$ and $B$ are sending notes of frequency $680 \ Hz$. $A$ listener moves from $A$ towards $B$ with a constant velocity $u$. If the speed of sound in air is $340 \ ms^{-1}$, what must be the value of $u$ so that he hears $10$ beats per second (in $ms^{-1}$)?

$A$ source is moving towards an observer with a speed of $20 \ m/s$ and having a frequency of $240 \ Hz$. The observer is now moving towards the source with a speed of $20 \ m/s$. If the velocity of sound is $340 \ m/s$,the apparent frequency heard by the observer is ... $Hz$.

An observer starts moving with uniform acceleration $a$ toward a stationary sound source emitting a whistle of frequency $n$. As the observer approaches the source,the apparent frequency $n'$ heard by the observer varies with time $t$ as:

Vedclass Test Series

Exam Paper Generator

Online Exam Module