Choose the appropriate motion model:
Constant velocity
Constant acceleration
General motion (velocity changes over time/space)
Use constant velocity:
(v = Delta x / Delta t)
Use constant acceleration:
(v = v_0 + at)
(v^2 = v_0^2 + 2aDelta x)
(v = (Delta x/Delta t) + frac{1}{2}aDelta t)
Use average velocity (any motion):
(v_{text{avg}} = Delta x / Delta t)
Use instantaneous velocity from position-time data:
(v(t) = dx/dt)
Use instantaneous velocity from a graph:
Slope of the position–time graph at the time of interest
Use instantaneous velocity from discrete measurements:
(v approx Delta x/Delta t) using a very small (Delta t)
Use velocity from acceleration-time data (if applicable):
(v(t) = v_0 + int a(t),dt)
Use velocity from displacement-time function:
If (x(t)) is known, compute (v(t) = d(x(t))/dt)
For vector velocity:
(vec{v} = dvec{r}/dt)
Components: (v_x = dx/dt,; v_y = dy/dt,; v_z = dz/dt)
Check units:
(m/s) (SI) or (ft/s) (US customary)