JEE Main 2022 · 28 Jul · Shift 1 · Physics Q57

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PhysicsInteger+4 / -1Question 57 of 90

The frequency of echo will be ______ Hz if the train blowing a whistle of frequency 320 Hz is moving with a velocity of 36 km/h towards a hill from which an echo is heard by the train driver. Velocity of sound in air is 330 m/s.

Your answer

Answer and worked solution

Official answer: 340

Echo heard by a moving observer from a moving source: $f'=f\frac{v+u}{v-u}=320\times\frac{340}{320}=340$ Hz.

Answer: 340

Topics:Doppler effect

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JEE Main 2022 · 28 Jul · Shift 1, Physics question 57