A large part of physics is the study of how things move. In this section, the motion that you experience in everyday life will be explained.



In order to describe how things move, we first must describe where they are. Coordinates are anyway to tell where a particle is. You can have a line, for example, where the coordinates might be described by the Real number line. You could also talk about two-dimensional coordinates, x and y, that tell you where things are on a rectangle.



Displacement is the change in the position of something.

For example, say we have the real number line with an ant at 0. If the ant moves to the 2, its displacement would be 2.

What if the ant moves from 0 to 2 to 5 and then to 2 again? Its displacement over the whole series of actions would still be 2, for displacement only measures the change in position after a series of actions. Its distance, however, would be 6.

Idea. Distance and displacement are not the same in physics.

Big Idea. Change is a very important concept in physics