Aman pushes a 60.8 kg crate across a rough surface with an applied force of 125 n and at a constant speed.

what is the magnitude of the force normal acting on the box?

Horizontal distance between two boats = x = 14 m

One boat is at trough, the other is at crest.

As there is no crests between them meaning the boat are next to each other.

Wavelength is the distance between two consecutive crests/troughs = w

The distance between a crest and a trough next to it = w/2

Complete cycles = c = 5

Time taken for c cycles = t = 15 s

Vertical distance between two boats = y = 2.4 m

wavelength = w = 2x = 28 m

Amplitude =  A = Displacement from mean to extreme position = y/2 = 1.2 m

Time period for one cycle = T = t/c = 15/5 = 3 s/cycle

frequency = 1/T = 1/3 = 0.33 hertz

speed = wavelength/Period = w/T = 28/3 = 9.33 m/s