# Describing Motion

## What is Motion?

The English definition of motion is the act, process, or instance of changing position. The physics definition is when something's distance from another object changes.

Whether or not an object is moving, it is relative to something else.

## How to tell if something is moving

The only sure way to tell if an object is in motion is to compare it to a still standing object called a point of reference. See the picture below with the man in the car and a tree? Is the car's position from the tree changing?

YES IT IS! Therefore, the car is in motion.

## Distance vs. Displacement

The total length of an actual path between 2 points is the distance. Let's say the distance between the mouse and the cheese is 10 cm. But what if there are mouse traps to stop the mouse from getting to the cheese. The length and direction an object moves from its starting point is the displacement. Although the actual length between the two points is 10 cm, the mouse must travel 30 cm in order to avoid certain doom.

## Vectors

Vectors are drawn as straight lines and represent the magnitude and direction of an object in motion.

## How does this affect the modern world?

Knowing how to calculate distance vs. displacement is neccesary to know how long to build roads, buildings, tracks and more. This knowledge affects and is depended on more things than most would originally think.