Home
Class 12
PHYSICS
A tuning moving towards a tunnel in a hu...

A tuning moving towards a tunnel in a huge mountain with a speed of `12 m//s` sounds its whistle. Sound is reflected from the mountain. If the driver hears `6` beats per second & speed of sound in air is `332 m//s`, the frequency of the whistle is

A

80 Hz

B

120 Hz

C

160Hz

D

240 Hz

Text Solution

Verified by Experts

The correct Answer is:
A
Let original frequency is f by the concept of Doppler effect frequency of reflected wave.
`f = (V + u)/(V - u) f = (332 + 12)/(332 - 12) xx f, f. - f = 6`
`344/320 f - f = 6 implies f = (320 xx 6)/(24) = 80 Hz`
Promotional Banner

Topper's Solved these Questions

  • WAVES

    PHYSICS WALLAH|Exercise NEET PAST 4 YEARS QUESTIONS |15 Videos

  • WAVES

    PHYSICS WALLAH|Exercise NEET PAST 4 YEARS QUESTIONS |15 Videos

  • WAVE OPTICS

    PHYSICS WALLAH|Exercise Neet Past 5 Years Questions|16 Videos

  • WORK, ENERGY AND POWER

    PHYSICS WALLAH|Exercise NEET Past 5 Years Questions|16 Videos

Similar Questions

Explore conceptually related problems

The minimum distance to hear echo (speed of sound in air is 340 m//s )

The echo of a sound is heard after 5 seconds. If the speed of sound in air be 342m/s, calculate the distance of the reflecting surface.

A boy is walking away from a well at a speed of 1.0 m//s in a direction at right angles to the wall. As he walks, he below a whistle steadily. An observer towards whom the boy is walking hears 4.0 beats per second. If the speed of sound is 340 m//s , what is the frequency of the whistle?

An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km, it blows a whistle whose echo is heard by the driver after 5 seconds. If the speed of sound in air is 330 m/s, then the speed of the engine is :

A man standing on a platform observes that the frequency of the sound of a whistle emitted by a train drops by 140 Hz. If the velocity of sound in air is 330 m/s and the speed of the train is 70 m/s, the frequency of the whistle is

A boy riding on a bicycle going at 12 km h^-1 towards a vertical wall whistles at his dog on the ground. If the frequency of the whistle is 1600 Hz and the speed of sound in air is 330 m s^-1, find (a) the frequency of the whistle as received by the wall (b) the frequency of the reflected whistle as received by the boy.

A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is f_(1) . If the speed of train is reduced to 17 m/s, the frequency registered is f_(2) . If speed fo sound is 340 m/s, then the ratio f_(1)//f_(2) is :

PHYSICS WALLAH-WAVES-LEVEL - 2
  1. The fundamental frequency of a closed organ pipe is same as the first ...

    Text Solution

    |

  2. The frequency of fork A is 3% more than the frequency of a standard fo...

    Text Solution

    |

  3. A tuning fork produces 6 beats/sec with sonometer wire when its tensio...

    Text Solution

    |

  4. A closed organ pipe and an open organ pipe of same length produce 4 be...

    Text Solution

    |

  5. An engine driver moving towards a wall with velocity of 50 ms^(-1) emi...

    Text Solution

    |

  6. A source of sound is travelling towards a stationary observer. The fre...

    Text Solution

    |

  7. Two tuning forks with natural frequencies of 340 Hz each move relative...

    Text Solution

    |

  8. If v1 and v2 are the frequencies of two turning forks, then beat frequ...

    Text Solution

    |

  9. The second overtone of an open pipe A and closed pipe B have the same ...

    Text Solution

    |

  10. There is a set of four tuning forks , one with the lowest frequency vi...

    Text Solution

    |

  11. A tuning moving towards a tunnel in a huge mountain with a speed of 12...

    Text Solution

    |

  12. Number of beats between A and B is 5 and between B and C are 3. Number...

    Text Solution

    |

  13. If the length of an open organ pipe is 33.3cm , then the frequency of ...

    Text Solution

    |

  14. Two sound sources emitting sound each of wavelength lambda are fixed a...

    Text Solution

    |

  15. A tuning fork when sounded with tuning fork of frequency 256 produces ...

    Text Solution

    |

  16. Equation of a progressive sound wave is y =a sin (400 pi t - (pi x)/(...

    Text Solution

    |

  17. Two identical flutes produce fundamental notes of frequency 300Hz at 2...

    Text Solution

    |

  18. The equation of a wave is given by y=a sin (100t-x/10) where x and ...

    Text Solution

    |

  19. Velocity of sound in a gaseous medium is 330 m s^(-1). If the pressure...

    Text Solution

    |

  20. The ratio of intensities between two coherent sound sources is 4:1 the...

    Text Solution

    |