Question

Difficulty: EasySound Waves, Echoes, Pitch, Loudness, and Quality

An echo sounder on a fishing boat emits an acoustic pulse vertically downward toward the seabed and detects the reflected signal 0.80 s0.80\text{ s} later. If the speed of sound in seawater is 1450 m/s1450\text{ m/s}, what is the depth of the sea in meters at this location?

Answer: 580 m

Answer

The depth of the sea is 580 m580\text{ m}.
An echo signal travels to the reflecting surface and back, covering twice the depth (2d=v×t2d = v \times t). Substituting v=1450 m/sv = 1450\text{ m/s} and t=0.80 st = 0.80\text{ s} gives 2d=1160 m2d = 1160\text{ m}, so the seabed depth d=580 md = 580\text{ m}.

Step-by-Step Solution

1
Identify the given physical quantities
Total travel time t=0.80 st = 0.80\text{ s} and speed of sound v=1450 m/sv = 1450\text{ m/s}.
An echo involves sound traveling to the seabed and back, so the recorded time represents a two-way journey.
2
Set up the distance equation for an echo
Total distance traveled by the sound pulse is 2d=v×t2d = v \times t.
Sound travels to the sea floor and reflects back to the ship, covering a total distance equal to twice the depth.
3
Calculate the depth dd
d=1450×0.802=580 md = \frac{1450 \times 0.80}{2} = 580\text{ m}.
Dividing the total round-trip distance by 2 yields the one-way depth.

Key Concept

Calculation of distance using sound echoes in a medium
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