Acceleration

Displacement and velocity

Displacement and velocity are both vector quantities.  This means that they have direction as well as size.  Displacement is distance in a given direction so it can be positive or negative.  Positive is forward travel and negative displacement is backward travel.

Velocity is speed in a given direction and it can be positive, or negative if an object is moving backwards.

Displacement-time graphs

• 0A - constant speed forwards
• AB - stationary
• BC - constant speed back to start
• CD - constant speed backwards
• DE - stationary
• EF - constant speed back towards start

Calculating speed from a graph

A - The speed is…