# What is velocity?

"Velocity" = (" Change in displacement " or trianglebarx)/( "Change in time " or trianglet )

#### Explanation:

To define the fastness of an motion , we need to find how fast the space coordinates ( position vector ) of a particle relative to a fixed reference point changes with time . It is called as " Velocity ".

Velocity is also defined as the rate of change of displacement .

Velocity is a vector quantity . It depends on both magnitude and direction of the object .

When a particle moves , it's positive vector $\overline{r}$ must change in direction or magnitude or both ,Velocity is defined as the rate of change in direction or magnitude of $\overline{r}$ with respect to time .

It is measured in $m {s}^{-} 1$ , $k m p h$ , $\text{ miles per hour }$ ,etc.

It has dimensional formula - $\left[{M}^{0} {L}^{1} {T}^{-} 1\right]$
or simply - $\left[L {T}^{-} 1\right]$