
Actually Welcome to the Concept of the Wave Optics.
Whenever the waves are out of phase they form a DESTRUCTIVE interference.
thus,
Destructive Interference occurs when two waves are out of phase.
Gravity pulls to the centre of the earth. A ship floats in water because the water pushing it up (upthrust) is equal to the force<span> of gravity (weight) pulling it </span>down<span>. Friction also occurs when objects move through air. This is </span>called<span>air resistance.</span>
There are 100 billion planets