## Calculus, 10th Edition (Anton)

Velocity is the change in displacement to the time taken ratio. In other words, velocity is the $rate$ of change of displacement with respect to time. $$\vec{v}=\lim\limits_{\Delta t \to 0}\frac{\Delta s}{\Delta t}=\frac{ds}{dt}$$, where $\Delta s$ represents change in displacement.