Question

Question #3d06a

Answer 1

Displacement is relative

Explanation:

So there's 2 types of movement measuring: distance and displacement.

Distance measures only how far you go from your initial coordinates, and the path. So imagine walking down a winding road- you don't care about where you're going, you're just measuring how much you walk.

Displacement, on the other hand finds the relative position of something to something else. So you're just looking at where something is in the beginning and the end.
But to do this, you need to compare where it is according to something else. (It would be pretty hard to tell where something is if you don't know what's around it.)

So let's say you're looking at where a pencil is. There's a book right behind the pencil. So you say that the pencil is in front of the book. Then you move the pencil behind the book (the same distance, if you measure with a ruler the distance between the pencil and the book, it's the same.) But then what's the difference between the 1st and 2nd scenario? Well, the pencil in the 2nd scenario is behind the book. This is what "negative" is. '

Down is negative of up while left is negative of right. (It can change according to different circumstances though, but this is how it is in a graph.)

This will become important when there are multiple objects. If you have a pencil 5 meters to the right of the book and an eraser 5 meters to the left, writing that "a pencil is 5 to one side of the book and an eraser is 5 to the left of the other side of the book" is way too long. You can just write that a "pencil is 5 from the book and the eraser is -5 from the book" (equation: pencil=book+5, eraser=book-5)