Question

The speed of sound in air and in sea-water is given to be 340 m/s and 1440 m/s resp. A ship sends a strong signal straight down and detects its echo after 1.5 m seconds. The depth of the sea at that point is

• A. 2.16 km
• B. 1.08 km
• C. 0.51 km
• D. 0.255 km

Answer 1

The correct option is B 1.08 km

If the depth of sea is taken as 'd', then the sound wave travels a total distance of 2d to reach back to the ship, therefore
$V=\frac{2d}{t}$
$1440=\frac{2d}{1.5}$
$d=\frac{1440\times 15}{2\times 10}=72\times 15=1080m$
$d=1.08km$