To study kinematics, that is, the description of the movements, we need to take into account some essential quantities, which are:

## Time interval

All the movements that we will study will happen from a certain moment, which we will call the initial moment and represent by** t****.**

**The time that elapses between two certain moments we call time interval.** We represent the time interval by . Its unit in the international system is the** second**.

We can mathematically represent the time interval by: |

## Position

Have you ever noticed those little signs on the roadside? They indicate the mileage, record the position of the car and allow you to locate on the road.

** Position of a furniture is its location in relation to a certain origin** .

We represent the position by **S.** Its unit in the international system is the **meter (m)**.

## Displacement

Suppose a person left kilometer 4 and is now at kilometer 8. His position varied 3 kilometers, right?

Your starting position, represented by **s _{0}**, is 4 km. Your final position is

**s**, and worth 8 km.

** The difference between two positions of a furniture is called displacement. **

We represent displacement by . Its unit in the International System is meter (m), and its mathematical representation is: |

Thus, the displacement of the person in question was as follows: