A particle is said to move with uniform velocity if it undergoes equal displacements in equal intervals of time, however small these intervals may be.
In this case, the velocity is equal to the displacement vector per unit time interval and is given by 
When a particle moves with uniform velocity, we always get the same value of 
from the above equation, irrespective of the values of t, t'. In order to obtain the formulae for uniform motion in two dimensions, we begin with the formulae for uniform motion in one dimension, which are,
The same formulae can be generalised for uniform motion in two dimensions in the following way
These formulae are applicable only to a point object moving uniformly in a straight line in the given plane.
Similarly, for uniform velocity,
where vx and vy are the rectangular components of along X-axis and Y-axis respectively.
The magnitude of , also known as speed, is given by 
We have in equation (4)
Equating coefficients of 
and 
on both sides of the above equation, we get the two following equations
Here, each rectangular position coordinate depends on time like the position coordinate of a uniform one dimensional position.
