Home
Class 11
PHYSICS
A car is moving with a speed of 72 km . ...

A car is moving with a speed of 72 km . `h^(-1)` towards a roadside source that emits sound at a frequency of 850 Hz. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is 340 m . `s^(-1)`, the difference of the two frequencies, the driver hears is

A

50 Hz

B

85 Hz

C

100 Hz

D

150 Hz

Text Solution

Verified by Experts

The correct Answer is:
C
Velocity of the car, `u_(o)=72 km cdot h^(-1) = 20 m cdot s^(-1)`
When the car is approaching the source, then apparent frequency is,
`n_(1) = ((V+u_(o))/V)n=((340+20)/340)850=900" Hz " `
When the car moves away from the source, then apparent frequency is,
`n_(2) = ((V+u_(o))/V)n=((340+20)/340)850=800" Hz " `
`therefore n_(1) - n_(2) =900-800=100` Hz
the option © is correct.
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • DOPPLER EFFECT IN SOUND

    CHHAYA PUBLICATION|Exercise EXAMINATION ARCHIVE WITH SOLUTIONS (JEE(Main))|2 Videos

  • DOPPLER EFFECT IN SOUND

    CHHAYA PUBLICATION|Exercise EXAMINATION ARCHIVE WITH SOLUTIONS (AIPMT)|1 Videos

  • DOPPLER EFFECT IN SOUND

    CHHAYA PUBLICATION|Exercise EXAMINATION ARCHIVE WITH SOLUTIONS (WBCHSE)|1 Videos

  • CIRCULAR MOTION

    CHHAYA PUBLICATION|Exercise CBSE SCANNER|11 Videos

  • ELASTICITY

    CHHAYA PUBLICATION|Exercise CBSE SCANNER|10 Videos

Similar Questions

Explore conceptually related problems

A car is moving with a speed of 72 "km-hour"^(-1) towards a roadside source that emits sound at a frequency of 850 Hz. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is 340 ms^(-1) , the difference of the two frequencies, the driver hears is

A car moving at a velocity of 17 ms^(-1) towards an approaching bus that blows a horn at a frequency of 640Hz on a straight track. The frequency of this horn appears to be 680 Hz to the car driver. If the velocity of sound in air is 340ms^(-1) , then the velocity of the approaching bus is

Knowledge Check

  • A car is moving with a speed of 72 km-hour^(-1) towards a roadside source that emits sound at a frequency of 850 Hz. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is 340 ms^(-1) , the difference of the two frequencies, the driver hears is

    A
    50 Hz
    B
    85 Hz
    C
    100 Hz
    D
    150 Hz

  • A car at a velocity of 17 ms^(-1) towards an approaching bus that blows a horn at a frequency of 640 Hz on a straight track. The frequency of this horn appears to be 680 Hz. To the car driver. If the velocity of sound in air is 340 ms^(-1), then the velocity of the approaching bus is

    A
    `2 ms^(-1)`
    B
    `4 ms^(-1)`
    C
    `8 ms^(-1)`
    D
    `10 ms^(-1)`

  • A train is moving with a uniform speed of 33 m/s and an observer is approaching the train with the same speed. If the train blows a whistle of frequency 1000 Hz and the velocity of sound is 333 m/s, then the apparent frequency of the sound that the observer hears is

    A
    1220 Hz
    B
    1099 Hz
    C
    1110 Hz
    D
    1200 Hz

    • Similar Questions

    Explore conceptually related problems

    A rocket is moving at a speed of 200 m s^(-1) towards a stationary target. While moving, it emits a wave of frequency 1000 Hz. Some of the sound reaching the target gets reflected back to the rocket as an echo. Calculate (1) the frequency of the sound as detected by the target and (2) the frequency of the echo as detected by the rocket.

    A moter car is moving towards a vertical wall . The driver abserves that the frequency of the sound of his horn changes from 440 Hz to 480 Hz when . If the velocity of sound is 330 m s^(-1) , what is the speed of the car ?

    A police standing at a place detected a 10% change in frequency of the sound of a horn of a fast moving car approaching towards him . If the velocity of sound is 340 m s^(-1) , what is the speed of the car ?

    A sound wave of frequency 80 Hz gets reflected noumally from a large wall. Estimate the distance of the first node and the first antinode from the wall. Given , velocity of sound in air = 320 m * s^(-1) .

    A train is moving with a uniform speed of 33 m/s and an observer is approaching the train with the same speed. If the train blows a whistle of frequency 1000 Hz and the velocity of sound is 333 m/s, then the apparent frequency of the sound that the observer hears is

    Home
    Profile