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Two vehicles, each moving with speed u on the same horizontal straight road, are approaching each other. Wind blows along the road with velocity w. One of these vehicles blows a whistle of frequency f1. An observer in the other vehicle hears the frequency of the whistle to be f2. The speed of sound in still air is V. The correct statement(s) is (are)
  • a)
    If the wind blows from the observer to the source, f2 > f1
  • b)
    If the wind blows from th e source to the observer, f2 > f1
  • c)
    If the wind blows from observer to the source, f2 < f1
  • d)
    If the wind blows from the source to the observer, f2 < f1
Correct answer is option 'A,B'. Can you explain this answer?
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Two vehicles, each moving with speed u on the same horizontal straight...

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Two vehicles, each moving with speed u on the same horizontal straight...
A) If the wind blows from the observer to the source, f2 > f1.
b) If the wind blows from the source to the observer, f2 < />

Explanation:

When the two vehicles are approaching each other, the relative velocity between them is (2u + w) if the wind is blowing from the observer to the source, and (2u - w) if the wind is blowing from the source to the observer.

The frequency of the whistle heard by the observer in the other vehicle is given by the Doppler effect formula:

f2 = f1 (V +/- vr) / (V +/- vs)

where V is the speed of sound in still air, vr is the relative velocity between the source and the wind, and vs is the relative velocity between the observer and the wind.

Substituting the values, we get:

a) If the wind blows from the observer to the source:

f2 = f1 (V + (2u + w)) / (V + w)

Since (2u + w) is positive, f2 will be greater than f1.

b) If the wind blows from the source to the observer:

f2 = f1 (V - (2u - w)) / (V - w)

Since (2u - w) is positive, f2 will be less than f1.

Therefore, the correct statement is (a).
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Two vehicles, each moving with speed u on the same horizontal straight road, are approaching each other. Wind blows along the road with velocity w. One of these vehicles blows a whistle of frequency f1. An observer in the other vehicle hears the frequency of the whistle to be f2. The speed of sound in still air is V. The correct statement(s) is (are)a)If the wind blows from the observer to the source, f2 > f1b)If the wind blows from th e source to the observer, f2 > f1c)If the wind blows from observer to the source, f2 < f1d)If the wind blows from the source to the observer, f2 < f1Correct answer is option 'A,B'. Can you explain this answer?
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Two vehicles, each moving with speed u on the same horizontal straight road, are approaching each other. Wind blows along the road with velocity w. One of these vehicles blows a whistle of frequency f1. An observer in the other vehicle hears the frequency of the whistle to be f2. The speed of sound in still air is V. The correct statement(s) is (are)a)If the wind blows from the observer to the source, f2 > f1b)If the wind blows from th e source to the observer, f2 > f1c)If the wind blows from observer to the source, f2 < f1d)If the wind blows from the source to the observer, f2 < f1Correct answer is option 'A,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 Two vehicles, each moving with speed u on the same horizontal straight road, are approaching each other. Wind blows along the road with velocity w. One of these vehicles blows a whistle of frequency f1. An observer in the other vehicle hears the frequency of the whistle to be f2. The speed of sound in still air is V. The correct statement(s) is (are)a)If the wind blows from the observer to the source, f2 > f1b)If the wind blows from th e source to the observer, f2 > f1c)If the wind blows from observer to the source, f2 < f1d)If the wind blows from the source to the observer, f2 < f1Correct answer is option 'A,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 Two vehicles, each moving with speed u on the same horizontal straight road, are approaching each other. Wind blows along the road with velocity w. One of these vehicles blows a whistle of frequency f1. An observer in the other vehicle hears the frequency of the whistle to be f2. The speed of sound in still air is V. The correct statement(s) is (are)a)If the wind blows from the observer to the source, f2 > f1b)If the wind blows from th e source to the observer, f2 > f1c)If the wind blows from observer to the source, f2 < f1d)If the wind blows from the source to the observer, f2 < f1Correct answer is option 'A,B'. Can you explain this answer?.
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