Question

 Two people are fishing from small boats located 28 m apart.Waves pass through the water, and each person’s boat bobs up and down 15 times in 1.0 min. At a time when one boat is on a crest, the other one is in a trough, and there is one crest between the two boats. What is the speed of the waves?

Answer 1

The speed is wavelength divided by period:

$$v=\dfrac \lambda T.$$

The period is 60/15=4 s. The wavelength:

$$\lambda=28/1.5=18.7\text{ m}.$$

So:

$$v=18.7/4=4.68\text{ m/s}.$$