This summer you go to the beach with some friends who cannot

This summer you go to the beach with some friends who cannot swim in large waves. While you are there, you notice that the waves crash on the shore every 4 seconds. You also notice that the speed of the waves is 5 meters per second. You look off shore and see a single channel for boats to come into the harbor. The channel is 100 meters wide and 1 km offshore. How far from the center of the channel should you take your friends to play in the waves?

Solution

Distance travelled by the wave is

          d = v t

              = ( 5 m /s ) ( 4 s )

              = 20 m

far from the ceter of channel is

            s = 1000 - 20 m = 980 m