If you're referring to the different colors that usually occur at the tip of missles, rockets and some other aircraft, it either a) signifies the end of a particular plate of metal, fabricated specifically to be for the nose. Sometimes these can even be a different alloy or metal all together. or b) this shows where the curved surface begins, so in the case of damage or imperfections due to wear, they can be repaired and measured more easily. The shape of the nose is extremely important for smooth flight, and a dent or bump formed on it can make the aircraft unstable. If you can measure from where the curve starts by the difference in color, it makes repairing or re-fabricating the part much easier. Many of these curves aren't as simple as they appear.
You asked the question twice I answered it on the last one
Answer:
The net force is 500N downwards
Explanation:
When Haley is trying to pull an object upward. The below forces are acting on the object.
Fp = 5500N
Fg = 6000N
because the force of gravity is more than the force of the pull.
Fnet = Fg - Fp = 6000N - 5500N = 500N
And, the direction of the resultant force is the direction of the larger force.
When something is hit harder just like when sound is turned up the waves become higher and more frequent like a zig zag more so then wavy.
Nuclear fusion in the core tries to blow the star apart. Gravity holds it together. Whoever designed that system really knew what he was doing. I'm kinda grateful to him.