(i) Which property of sound wave determines : (a) loudness (b) pitch ? (ii) A SONAR station picks up a return signal after 3 seconds. How far away is the object ? (Speed of sound in water is 1440 m s^-1)

CBSE Class 9 CBSE Class 9 Science
1

(i) Which property of sound wave determines : (afloudness (b) pitch ?
(ii) A SONAR station picks up a return signal after 3 seconds. How far away is the object ? (Speed of sound in water is 1440 m s^-1)
(iii) How can reverberations in a big hall or auditorium be reduced ?

2

(i) (a) Loudness — amplitude
(b) Pitch — frequency

(ii) Given: t = 3 s, V = 1440 m s^-1, S = ?
Using the expression S = V x t/2 = 1440 x 3/2 = 2160 m

(iii) Reverberation can be reduced by covering the roof and walls with sound absorbent materials like compressed fibreboard, rough plaster or draperies. The seat materials also covered with sound absorbing properties.