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Page No 168: - Chapter 12 - Sound - Ncert Solutions class 9 - Science


Question 1:

An echo returned in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 m s−1?

Answer:

Speed of sound, v = 342 m s−1

Echo returns in time, t = 3 s

Distance travelled by sound = v × = 342 × 3 = 1026 m

In the given time interval, sound has to travel a distance that is twice the distance of the reflecting surface and the source.

Hence, the distance of the reflecting surface from the sourcehttps://img-nm.mnimgs.com/img/study_content/curr/1/9/8/124/1286/Chapter%2012_html_4ff63842.gif