6. (15 points) On a ship, it was decided to determine the depth of the ocean at their location. The signal sent by the sonar was received on the ship after 8 s. The speed of sound in water is 1.5 km/s. Determine the depth of the ocean.
Answer: $6000 \mathrm{m}$.

Solution. The distance traveled by sound $s=v t=1500 \cdot 8=12000$ m. Considering that the sound travels from the ship to the bottom and back, we get the depth $h=\frac{s}{2}=6000 \mathrm{m}$.

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