Physics for IGCSE & O level - Waves And Sounds (Section 3 - No. 27)
If a pulse of ultrasound takes 0.03 seconds to travel from a boat to the sea-bed and return, and the speed of sound in water is 1400 m/s, what is the water depth?
21 m
42 m
84 m
126 m
คำอธิบาย
Depth = 1/2 * Speed * time = 0.5 * 1400 m/s * 0.03 s = 21m