Question

A boat is floating at rest in a dense fog near a large cliff. The captain sounds its horn at water level and the sound travels through the salt water (1470 m/s) and the air (340m/s). The echo in the water (due to the cliff) takes 0.40s to return. How much additional time will it take for the echo in the air to travel?

Answer 1

$l/1470=0.4\to l=588(m)$

$588/340=1.73(s)$

$1.73-0.4=1.33(s)$ . Answer