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A source of sound A emitting waves of frequency 1800 Hz is falling towards ground with a terminal speed v. The observer B on the ground directly beneath the source receives waves of frequency 2150 Hz. The source A receives waves, reflected from ground, of frequency nearly : (Speed of sound =343 m/s)
  • a)
    2150 Hz
  • b)
    2500 Hz
  • c)
    1800 Hz
  • d)
    2400 Hz
Correct answer is option 'B'. Can you explain this answer?
Verified Answer
A source of sound A emitting waves of frequency 1800 Hz is falling tow...
By using Doppler effect,

The velocity from the above expression is,

v = 55.8 m/s
The reflected frequency is,

= 2500 Hz
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Most Upvoted Answer
A source of sound A emitting waves of frequency 1800 Hz is falling tow...
Explanation:

When the source A is falling towards the ground, the frequency of the waves emitted by the source is affected by the Doppler effect. The Doppler effect is the change in frequency or wavelength of a wave for an observer moving relative to the source of the wave.

Observer B on the ground:
The observer B on the ground receives waves of frequency 2150 Hz. This is the frequency observed by an observer when the source is moving towards them. We can use the Doppler effect equation for frequency to find the frequency observed by the observer:

f' = (v + v₀) / (v + vs) * f

where f' is the observed frequency, f is the emitted frequency, v is the velocity of sound in air, v₀ is the velocity of the observer (which is 0 as the observer is stationary on the ground), and vs is the velocity of the source.

Plugging in the given values:
f' = (343 + 0) / (343 + vs) * 1800 Hz
2150 Hz = 1800 Hz * (343 / (343 + vs))

Source A:
The source A receives waves reflected from the ground. When a wave is reflected from a moving object, the frequency of the reflected wave is affected by the Doppler effect as well. In this case, the source is moving towards the observer, so the frequency of the reflected wave will be higher than the emitted frequency.

Using the same Doppler effect equation, we can find the frequency observed by the source:
f' = (v + v₀) / (v + vs) * f

Plugging in the given values:
f' = (343 + 0) / (343 + vs) * 2150 Hz
f' = 2150 Hz * (343 / (343 + vs))

Since the source is moving towards the observer, the frequency observed by the source will be higher than the emitted frequency.

Conclusion:
Comparing the two equations, we can see that the observed frequency by the source A is higher than the observed frequency by the observer B. Therefore, the frequency received by the source A, reflected from the ground, will be higher than 2150 Hz.

The correct answer is option 'B' - 2500 Hz.
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A source of sound A emitting waves of frequency 1800 Hz is falling towards ground with a terminal speed v. The observer B on the ground directly beneath the source receives waves of frequency 2150 Hz. The source A receives waves, reflected from ground, of frequency nearly : (Speed of sound =343 m/s)a)2150 Hzb)2500 Hzc)1800 Hzd)2400 HzCorrect answer is option 'B'. Can you explain this answer?
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A source of sound A emitting waves of frequency 1800 Hz is falling towards ground with a terminal speed v. The observer B on the ground directly beneath the source receives waves of frequency 2150 Hz. The source A receives waves, reflected from ground, of frequency nearly : (Speed of sound =343 m/s)a)2150 Hzb)2500 Hzc)1800 Hzd)2400 HzCorrect answer is option 'B'. Can you explain this answer? for JEE 2024 is part of JEE preparation. The Question and answers have been prepared according to the JEE exam syllabus. Information about A source of sound A emitting waves of frequency 1800 Hz is falling towards ground with a terminal speed v. The observer B on the ground directly beneath the source receives waves of frequency 2150 Hz. The source A receives waves, reflected from ground, of frequency nearly : (Speed of sound =343 m/s)a)2150 Hzb)2500 Hzc)1800 Hzd)2400 HzCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for JEE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A source of sound A emitting waves of frequency 1800 Hz is falling towards ground with a terminal speed v. The observer B on the ground directly beneath the source receives waves of frequency 2150 Hz. The source A receives waves, reflected from ground, of frequency nearly : (Speed of sound =343 m/s)a)2150 Hzb)2500 Hzc)1800 Hzd)2400 HzCorrect answer is option 'B'. Can you explain this answer?.
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