You can use two-dimensional vectors to describe motion in a plane.

If a particle starts from the point with position vector (\boldr₀₎ and moves with constant velocity (\bold{v}), then its displacement from its initial position at time (t) is (\bold{v}t) and its position vector (\bold{r}) is given by (\bold{r} = \bold{r}_0 + \bold{v}t).

Vectors can be written in column notation or (\bold{i}-\bold{j}) notation.

For an object moving in a plane with constant acceleration:

(\bold{v} = \bold{u} + \bold{a}t )

(\bold{r} = \bold{u}t + \frac{1}{2}\bold{a}t² )

where

(\bold{r}) is the displacement at time (t)
(\bold{u}) is the initial velocity
(\bold{v}) is the velocity at time (t)
(\bold{a}) is the acceleration

[b]uVector formulae for constant acceleration for motion in a plane[/u]/b

(\bold{r} = \boldr₀ + \bold{v}t)

(\bold{v} = \bold{u} + \bold{a}t )

(\bold{r} = \bold{u}t + \frac{1}{2}\bold{a}t² )