The best answer is that it reduces the level of ground water
Answer:
When displacement is zero, the particle may be at rest, therefore, distance travelled = 0.
Again, when displacement is zero, the final position matches with the initial position after some time, but the distance travelled will not be zero.
In the diagram, the ship send sound(?) waves to the water, to determine if there is anything there. If there is something like a sunken ship shown in the diagram, the waves return in a shorter time hence you can understand if theres something or now. This is the principle of radars and sonars.
Answer:
High density D answers to your questions
