Waves are observed passing under a dock. wave crests are 8.0 meters apart. the time for a complete wave to pass by is 4.0 seconds. the markings on the post submerged in water indicate that the water level fluctuates from a trough at 6.0 meters to a crest at 9.0 meters. what is the wavelength of the wave?

Wavelength = 8 m

Explanation:

As we know that wavelength is the distance moved by the wave in one time period of the wave.

Here we know that wavelength can be defined either by distance between two consecutive crest or two consecutive trough.

Here we know that it is given that crest on the wave is 8 meter apart which means the distance between two consecutive crest  is 8 meters.

So here distance traveled by the wave in one complete time period that is given as 4 s is wavelength of wave which is given here as 8 meter

so here we can say

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.