Echo Sounding | Physics for Grade 10 PDF Download

What is Echo Sounding

• Echo sounding uses ultrasound to detect objects underwater
• The sound wave is reflected off the ocean bottom
• The time it takes for the sound wave to return is used to calculate the depth of the water
• The distance the wave travels is twice the depth of the ocean
  • This is the distance to the ocean floor plus the distance for the wave to return

Echo sounding is used to determine water depth

Worked Example

Step 1: List the known quantities
Wave speed, v = 1500 m/s
Time, t = 0.12 s
Step 2: Write out the wave speed, distance and time formula

Step 3: Rearrange the equation to make distance (x) the subject
x = v × t
Step 4: Put known values into the equation
x = 1500 × 0.12 = 180 m
Step 5: Half the distance to obtain the depth
d = 180 ÷ 2
Depth, d = 90 m

Exam Tip

• Don't forget to take into account that the sound wave has travelled twice the distance.
  You can do this one of two ways:
• Halve the time at the beginning, or
• Halve the distance at the end