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  1. Class 9
  2. Chapter 12 Class 9 - Sound

Transcript

Example 12.1 A sound wave has a frequency of 2 kHz and wave length 35 cm. How long will it take to travel 1.5 km? Frequency of sound = f = 2 kHz = 2000 Hz Wavelength = ๐œ† = 35 cm = 35/100 m = 0.35 m Distance travelled = d = 1.5 km = 1.5 km ร— 1000 = 15/10 ร— 1000 = 1500 m We know that, Speed of sound = Wavelength ร— Frequency v = ๐œ† ร— f v = 0.35 ร— 2000 v = 35/100 ร— 2000 v = 700 m/s We know that, Speed = ๐ท๐‘–๐‘ ๐‘ก๐‘Ž๐‘›๐‘๐‘’/๐‘‡๐‘–๐‘š๐‘’ Time = ๐ท๐‘–๐‘ ๐‘ก๐‘Ž๐‘›๐‘๐‘’/(๐‘†๐‘๐‘’๐‘’๐‘‘ ๐‘œ๐‘“ ๐‘ ๐‘œ๐‘ข๐‘›๐‘‘) = 1500/700 = 15/7 = 2.1 s Time taken by sound is 2.1 s

About the Author

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.