Thus, scientists use a graphical method called vectors to help calculate the sum of velocities in a given direction. The way this works is that you draw a picture with lines or arrows representing different velocities. Combining the speed with the direction of the arrow, you get its velocity. This can be a very handy tool in such a calculation. Acceleration Acceleration is the increase of velocity over a period of time.
Deceleration is the decrease of velocity.
In conclusion Motion is change in position. All motion is relative to some fixed point or object. Speed is a measurement of that change in position over time. Velocity is speed in a given direction. Vectors help to determine the sum of velocities.