Velocity
A vector quantity expressing the time rate of change of position, possessing both speed and direction.
Governing formula
v = dr/dt
SI unit
m/s
In depth
Speed is the scalar magnitude of velocity. An object moving in a circle at constant speed undergoes changing velocity because its direction changes continuously, experiencing acceleration.
Examples in the real world
An aircraft flying at 800 km/h due East, or a satellite orbiting Earth at 7.8 km/s.