Question

If you were standing at the end of a pier with a stopwatch in hand, how would you measure the average wave period of the waves that pass by? •Why do successive (one after the other) waves that arrive at the beach have different heights?

Answer 1

start the stopwatch just after a wave reaches the pier.count 10 more wave speak reaches the pier. Stop the stopwatch when the 10th peak reaches the pier. 

Period of one wave = P = (Time measured) ⁄ 10 

Frequency = f = 1 ⁄ P