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One train is approaching an observer at ...

One train is approaching an observer at rest and another train is receding from him with the same velocity `4 m//s` . Both trains blow whistles of same frequency of `243 H_(Z)` . The beat frequency in `H_(Z)` as heard by observer is (speed of sound in air = `320 m//s`)

A

`10`

B

`6`

C

`4`

D

`1`

Text Solution

Verified by Experts

The correct Answer is:
B
`f_(b) = 243 ((320) / (320 - 4 ))- 243 ((320)/ (320 + 4)) = 6 H_(Z)`
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DC PANDEY-SOUND WAVES-Level 1 Objective
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  4. Two sound waves of wavelengths lambda(1) and lambda(2) (lambda (2) gt ...

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  5. A, Band C are three tuning forks. Frequency of A is 350 H(Z) . Beats p...

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  6. The first resonance length of a resonance tube is 40 cm and the second...

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  7. Two identical wires are streched by the same tension of 100 N and each...

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  8. A tuning fork of frequency 340 Hz is excited and held above a cylindri...

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  9. In a closed end pipe of length 105 cm , standing waves are set up corr...

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  10. Oxygen is 16 times heavier than hydrogen. At NTP equal volumn of hydro...

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  11. A train is moving towards a stationary observer. Which of the followin...

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

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  13. One train is approaching an observer at rest and another train is rece...

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  14. Speed of sound in air is 320 m//s . A pipe closed at one end has a len...

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  15. Four sources of sound each of sound level 10 dB are sounded together i...

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  16. A longitudinal sound wave given by p = 2.5 sin.(pi)/(2) (x - 600 t) (p...

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  17. Sound waves of frequency 600 H(Z) fall normally on perfectly reflectin...

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  18. The wavelength of two sound waves are 49 cm and 50 cm , respectively ....

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  19. Two persons A and B , each carring a source of frequency 300 H(Z) , ar...

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  20. A fixed source of sound emitting a certain frequency appears as f(a) w...

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