D. used by the entire scientific community
B. more accurate system of measurement
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.
P = density × gravity acceleration × height
P = 1200 × 9.81 × 15/100
P = 1765.8