The minimum distance between the source of the sound and the obstacle for an echo (at 20°to take place is:
A. 17.2 m
B. 1.72 m
C. 17.8 m
D. 34.4 m
Answer:A
The minimum distance between the source of the sound and the obstacle for an echo (at 20°to take place is:
A. 17.2 m B. 1.72 m C. 17.8 m D. 34.4 m