Velocity
Velocity is a measure of how fast something moves in a particular direction.[1] In other words, a velocity is a speed with a direction. For instance, if an object moves east at 7 metres per second (7 m/s), we would say that its velocity is 7 m/s to the east.
To calculate the velocity of an object, we divide its displacement (its change of position) by the time it took to change position.[1]
[math]\displaystyle{ \text{velocity} = \frac\text{displacement}\text{time} }[/math]
For example, if an object moves 20 meters (m) to the left in 4 seconds (s), its velocity (v) would be equal to:
[math]\displaystyle{ \text{v} = \frac\text{20 m}\text{4 s} = \text{5 m/s to the left} }[/math]
A change in velocity is acceleration