Question

A stationary boat in the ocean is experiencing waves from a storm. the waves move at 56 km/h and have a wavelength of 160 m, both typical values. the boat is at the crest of a wave. how much time elapses until the boat is first at the trough of a wave?

Answer 1

The wavelength
`\lambda` of the wave is 160 m, and this is the distance between two consecutive crests. The boat is located at a crest of the wave, this means that the first trough is located 80 meters from the boat (because the distance between a crest and a trough is half the wavelength).

The speed of the wave is

`v=56 km/h = 15.6 m/s`
so the time the boat takes to reach the first trough is

`t= (S)/(v) = (80 m)/(15.6 m/s)=5.1 s`