AP EAMCET · PHYSICS · Waves and Sound
Two trains \(A\) and \(B\) are moving towards each other with speeds \(72 \mathrm{kmh}^{-1}\) and \(36 \mathrm{kmh}^{-1}\) respectively. The train \(A\) whistles at \(640 \mathrm{~Hz}\) frequency. Before the trains meet, frequency of sound heard by a passenger in Train \(B\) is
( Speed of sound in air \(=340 \mathrm{~ms}^{-1}\) ).
- A \(500 \mathrm{~Hz}\)
- B \(600 \mathrm{~Hz}\)
- C \(700 \mathrm{~Hz}\)
- D \(800 \mathrm{~Hz}\)
Answer & Solution
Correct Answer
(C) \(700 \mathrm{~Hz}\)
Step-by-step Solution
Detailed explanation
Apparent frequency due to doppler's shift when both observer \(O\) and source are approaching to each other, is given by apparent frequency, \(f^{\prime}=f\left(\frac{v+v_0}{v-v_s}\right)\)...(i) Here, \(v_o=\) observers speed \(=36 \mathrm{~km} / \mathrm{h}\)…
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