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.
Answer (integer)
340
Solution
<p>${v_s} = 36 \times {5 \over {18}} = 10$ m/sec</p>
<p>$f = {{v + {v_s}} \over {v - {v_s}}}{f_0}$</p>
<p>$= {{340} \over {320}} \times 320$</p>
<p>$= 340$ Hz</p>
About this question
Subject: Physics · Chapter: Waves · Topic: Wave Motion and Types
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