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An observer is standing stationary in air moving at a speed of 2m/s. A source of frequency 20Hz is moving in the direction of wind with speed 10m/s towards the observer. What will be the frequency as heard by the observer? Speed of sound in air is 330m/s.
  • a)
    20.62Hz
  • b)
    19.40Hz
  • c)
    21.68Hz
  • d)
    22.63Hz
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
An observer is standing stationary in air moving at a speed of 2m/s. A...
Given:
Observer's speed (vo) = 2 m/s
Speed of sound (v) = 330 m/s
Source frequency (f) = 20 Hz
Source speed (vs) = 10 m/s

To find:
Frequency as heard by the observer

Explanation:
When a source of sound and an observer are in relative motion, the frequency of the sound heard by the observer is given by the Doppler's effect formula:

f' = (v + vo) / (v + vs) * f

where f' is the frequency as heard by the observer.

Applying the formula:
Substituting the given values into the formula, we get:

f' = (330 + 2) / (330 + 10) * 20

Simplifying the expression:

f' = 332 / 340 * 20

f' = 332 / 17

f' ≈ 19.53 Hz

Rounding off to two decimal places, the frequency as heard by the observer is approximately 19.53 Hz.

Conclusion:
The frequency as heard by the observer is approximately 19.53 Hz. However, none of the given options match this value. Therefore, none of the options provided is correct.
Free Test
Community Answer
An observer is standing stationary in air moving at a speed of 2m/s. A...
As the air is moving, we can solve this question from the air’s frame of reference. From the air’s frame of reference, the observer will be going towards the observer at 2m/s and the source will be coming towards the observer at 10-2 = 8m/s.
F = f(v+v0)/(v+v8)
= 20(330+2)/(330-8)
= 20*332/322 = 20.62Hz.
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An observer is standing stationary in air moving at a speed of 2m/s. A source of frequency 20Hz is moving in the direction of wind with speed 10m/s towards the observer. What will be the frequency as heard by the observer? Speed of sound in air is 330m/s.a)20.62Hzb)19.40Hzc)21.68Hzd)22.63HzCorrect answer is option 'A'. Can you explain this answer?
Question Description
An observer is standing stationary in air moving at a speed of 2m/s. A source of frequency 20Hz is moving in the direction of wind with speed 10m/s towards the observer. What will be the frequency as heard by the observer? Speed of sound in air is 330m/s.a)20.62Hzb)19.40Hzc)21.68Hzd)22.63HzCorrect answer is option 'A'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about An observer is standing stationary in air moving at a speed of 2m/s. A source of frequency 20Hz is moving in the direction of wind with speed 10m/s towards the observer. What will be the frequency as heard by the observer? Speed of sound in air is 330m/s.a)20.62Hzb)19.40Hzc)21.68Hzd)22.63HzCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An observer is standing stationary in air moving at a speed of 2m/s. A source of frequency 20Hz is moving in the direction of wind with speed 10m/s towards the observer. What will be the frequency as heard by the observer? Speed of sound in air is 330m/s.a)20.62Hzb)19.40Hzc)21.68Hzd)22.63HzCorrect answer is option 'A'. Can you explain this answer?.
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