# What is the common difference between partial time derivative and ordinary time derivative? [duplicate]

What is difference between partial and ordinary time derivative? for example: what is difference between $\frac {\partial v}{\partial t}$ and $\frac {dv}{dt}$?

where the $v$ is velocity.

## marked as duplicate by Ben Crowell, Qmechanic♦May 3 '13 at 21:57

$$v =v(t,x,y)$$
$$\frac{dv}{dt} = \frac{\partial v}{\partial t}+ \frac{\partial v}{\partial x}\frac{\partial x}{\partial t} +\frac{\partial v}{\partial y}\frac{\partial y}{\partial t}$$
If we assume that $t$, $x$, and $y$ could be functions of the other variables as well.