Velocity and Acceleration
Velocity is speed in a given direction.
Two moving objects can have the same speed but a different velocity, e.g- cars moving down different sides of the motorway may have the same speed but are moving in different directions.
The acceleration of an object is its chnage in velocity per second.
The unit of acceleration is metres per second squared.
Acceleration = change in velocity / time taken for the change
A car decelerates when the driver brakes, we use the term deceleration or negative acceleration for any situation where an object slows down.