Velocity is the measurement of speed included with a direction. Both speed and direction are measured relative to some fixed object (in most cases, our planet earth). The numerical value of speed can be represented as a negative, which would indicate the opposite direction as indicated.
Velocity can be calculated from by the following expression:
The arrow above the velocity variable v indicates that it is a vector variable, and has some direction.
Velocity unit converter
Please see below to convert among various units for velocity:
The train was moving at 50 km/h west.
- 50km/h represents the speed
- West indicates the direction.
The Frisbee was thrown with a horizontal velocity of 10 m/s
- 10 m/s represents the speed
- the direction is horizontal, meaning the speed measurement is not accounting for the speed the Frisbee is falling
After the accident, the car was traveling at a velocity of -2 km/h
- The speed of the vehicle is 2km/h
- The direction would be the opposite direction which the vehicle is facing (intuitive deduction)
Hyperphysics has a more detailed discussion of velocity.