While navigating in fog off a coastline of steep cliffs, you hear the echo of the ships fog horn 6 seconds after the signal was sounded. What is the distance to the shore?

Correct Answer: Option A — 1100 yards

Sound travels at approximately 1100 feet per second. With an echo time of 6 seconds, the sound travels 6600 feet to the cliff and back. The distance to the shore is half the total travel distance, which is 3300 feet, or 1100 yards. This is a standard navigational application of acoustics.