Velocity includes the speed of an object and the direction of its motion.  While speed consists of the direction of an object, velocity does not.  So, for example, if a severe storm is headed your way, it’s essential to know the speed at which it’s traveling and the direction the storm is heading.

Acceleration is the rate of change of velocity.  Acceleration occurs when an object changes speed, direction, or both.  To calculate the acceleration of an object, the change in velocity is divided by the length of the time interval over which the change occurred.

Accelerating quickly puts a lot of force on an object.  Acceleration can be positive or negative, depending on the speed and direction. Positive acceleration can be seen when a plane speeds up to take off. Negative acceleration can be seen when a bike slows down.

Review:

1. Define velocity.
2. When does acceleration occur?
3. Compare positive acceleration to negative acceleration.