Answer:
The wave speed is calculated below:
Explanation:
Given,
number of waves passed per minute = 8
time period = 1 minute = 60 s
distance between successive wave crests = 20 m
waves passing interval per second =

Now,
wave speed = 20 m ×

=
m/s
= 2.67 m/s
Hence the wave speed is 2.67 m/s.
This method is known as linear perspective.
When using linear perspective, artists use a set of drawn or imaginary lines which are made to converge at the horizon of the image. These lines change the viewer's perspective by providing a point through which the relative size, shape and position of objects is determined. This technique creates the illusion of depth.
The answer of this question is 0.6m/s