Boats use echo sounders. Pulses of sound waves are reflected by the sea bed and

detected by a sensitive microphone. The time between an echo sounder sending and

receiving a pulse is 0.005 s. The device calculates the depth of the sea, using the speed

of sound in sea water, which is 1500 m/s.

Use this information to calculate the depth of the sea. Show your working.

Answer: depth = 3.75 m

Explanation:

Taken the speed of the sound in sea to be V = 1500 m/s

The time between an echo sounder sending and receiving a pulse is 0.005 s. That is,

Total time T = 0.005

Formula for echo is:

V = 2X/T

Where X = distance covered

Substitute V and T into the formula

1500 = 2X/0.005

Cross multiply

7.5 = 2X

Make X the subject of formula

X = 7.5/2

X = 3.75 m

Therefore, the depth of the sea is 3.75 m