Question:
Two engines pass each other moving in opposite directions with uniform speed of \(30\ \mathrm{m/s}\). One of them is blowing a whistle of frequency \(540\ \mathrm{Hz}\). Calculate the frequency heard by driver of second engine before they pass each other. Speed of sound is \(330\ \mathrm{m/sec}\) :
Two engines pass each other moving in opposite directions with uniform speed of \(30\ \mathrm{m/s}\). One of them is blowing a whistle of frequency \(540\ \mathrm{Hz}\). Calculate the frequency heard by driver of second engine before they pass each other. Speed of sound is \(330\ \mathrm{m/sec}\) :
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Before passing, the engines approach each other, so the observer hears a higher frequency: \(f' = f\frac{v+v_o}{v-v_s}\).
Updated On: Nov 11, 2026
- 450 Hz
- 540 Hz
- 648 Hz
- 270 Hz
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The Correct Option is C
Solution and Explanation
Before crossing, source and observer approach each other, so the apparent frequency is \(f' = f\,\frac{v+v_o}{v-v_s} = 540\times\frac{330+30}{330-30} = 540\times\frac{360}{300} = 648\ \mathrm{Hz}\).
Answer: (3) 648 Hz
Answer: (3) 648 Hz
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