Question

A fisherman passes the time by counting waves passing under his boat. He notices that his boat rises and falls 8 times in 65 seconds. He counts 6 wave crests between his boat and a buoy located 54 m away. What is the speed of the water waves?

Answer 1

Since we know that frequency=number of waves per second

then frequency of water waves

f = 8/65

=0.1231 Hz

The distance between two consecutive crests or troughs is known as wavelength(λ)

Hence the distance between the six crests will be 6λ

But the distance between any crest and trough is λ/2

hence total distance is;

(6+0.5)λ=6.5λ

but λ=54 m

total distance =54×6.5

=351 m

we know that;

velocity(v)=fλ

= 0.1231 Hz × 351 m

=43.21 m/s