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Paragraph: Two trains A and B are moving with speeds 20 ~m / s and 30 ~m / s , respectively in the same direction on the same straight track, with B ahead of A . The engines are at the front ends. The engine of train A blows a long whistle. Assume that the sound of the whistle is composed of components varying in frequency from f₁=800 ~Hz to f₂=1120 ~Hz , as shown in the figure. The spread in the frequency (highest f

Correct answer

0

Step-by-step solution

For the passengers in train A , there is no relative motion between source and observe, as both are moving with velocity 20 ~m / s . Therefore, there is no change in observed frequencies and correspondingly there is no change in their intensities. Therefore, the correct option is (a).

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