Question

Question no. 2 & 3

2. Calculate the minimum distance in air required between the source of sound and the obstacle to hear an echo. Take speed on sound in air = 350 m s^-1. Ans. 17.5 m.

3. What should be the minimum distance between resource and reflector in water so that echo is heard distinctly ?
( The speed of sound in water = 1400 m s^-1). Ans. 70 m.

Answer 1

minimum distance d=0.1*350/2=17.5 m
minimum distnace in water d=0.1*1400/2=70 m