Question

1. A crest of a water wave requires 5.2 s to travel between two points on a fishing pier located 

19 m apart. It is noted in a series of waves that 20 crests pass the first point in 17 s. What is the wavelength of the waves?

Answer 1

$$v=19/5.2=6.35\text{ m/s}.\\ \lambda=vt/n=6.35·17/20=5.40\text{ m}.$$