P9 - Motion

• Distance-time graph: A graph that shows the distance travelled by an object from its starting point at a certain time. Slope means object is moving because distance changes. If line is horizontal then object not moving as distance isn't changing. Gradient shows speed.

  
• Acceleration is how quick the velocity changes. Vector quantity. Acceleration shown on d-t graph by curved line.
• Velocity-time graphs show velocity of an object at any time of a journey. Gradient of a slope shows acceleration. Distance travelled is area under the graph.

  
• Freefalling object initially accelerates due to gravity but air resistance/friction increases with speed until forces are balanced. Object now falling at terminal velocity.