Acceleration
The vector rate of change of velocity with respect to time.
Governing formula
a = dv/dt = d²r/dt²
SI unit
m/s²
In depth
Acceleration occurs whenever an object speeds up, slows down (deceleration), or changes direction. Net force and acceleration are always collinear.
Examples in the real world
A dragster accelerating from 0 to 100 km/h in 1.5 seconds, or a planet accelerating toward the Sun in orbit.