It is a windy day and there are waves on the surface of the open ocean. The wave crests are 40 feet apart and 5 feet above the troughs as they pass a school of fish. The waves push on fish and making them accelerate. The fish do not like this jostling, so to avoid it almost completely the fish should swim
A) as fast as possible.
B) at least 5 feet below the surface of the water.
C) as close to the surface of the water as possible.
D) at least 20 feet below the surface of the water.

Question

Quizplus · Accepted Answer

Waves have a diminishing effect with depth, and their influence extends to a depth of about half the wavelength. Since the wavelength (distance between crests) is 40 feet, the wave effect significantly diminishes at depths beyond half of this, which is 20 feet. Swimming at least 20 feet below the surface would allow the fish to avoid the wave-induced motion almost completely.

It Is a Windy Day and There Are Waves on the Surface