# Kinematics

**Kinematics** is the part of classical mechanics that studies the motion of a *particle*, ignoring its causes.

A *particle* is a point-like mass having infinitesimal size. This abstraction allows to simplify the observation of motion, as it gets rid of the complications deriving from the extension of real bodies. Moreover this abstraction is introductory to the far more complex study of real bodies.

**Kinematics of the material point**, as said by its name, studies the motion of a point-like object.

## Terms to know

- Time (Δt)
- The duration of an observation or action. We always consider time to be the
**independent**variable in kinematics. This means that in distance-time, position-time and acceleration-time graphs, time is always on the x-axis. Δt = t2 – t1 is the time between some start time t1 and some end time t2. We can define those times any way we like, as is convenient for the situation.

- Scalar
- A quantity that has only a magnitude (size) and no direction. e.g. 900kg

- Vector
- A quantity that has both a magnitude (size) and a direction. e.g. 900 km [West]. To show a quantity is a vector we usually put a half-arrow (→) above that quantity or bold the variable letter (e.g. position is written as a bold
**p**).

bozemanscience - tutorials for sciences (both regular and AP).