Acceleration-Time Graphs (Edexcel International A Level Maths): Revision Note

Acceleration-Time Graphs

What is an acceleration-time graph?

• Acceleration-time graphs show the acceleration of an object as it moves in a straight line

• They show acceleration (on the vertical axis) against time (on the horizontal axis)

• Acceleration-time graphs can go below the horizontal axis

What are the key features of an acceleration-time graph?

• A horizontal line shows that the object is accelerating at a constant rate

• If the graph touches the x-axis then the object is moving with constant velocity at that time

• If the graph is above the x-axis then the object has positive acceleration and its velocity is increasing which means

  • It is speeding up if it is moving forward

  • It is slowing down if it is moving backwards

• If the graph is below the x-axis then the object has negative acceleration and its velocity is decreasing which means

  • It is slowing down if it is moving forward

  • It is speeding up if it is moving backwards

• The area between graph and the x-axis tells us the change in velocity of the object

  • Graph above the x-axis means the velocity of the object is increasing

  • Graph below the x-axis means the velocity of the object is decreasing

• The total change in velocity of the object from its starting point is the sum of the areas above the x-axis minus the sum of the areas below the x-axis

  

What does an acceleration-time graph NOT show?

• You can not tell the velocity of the object at a specific time just by looking at an acceleration-time graph

  • You can calculate this using the areas between the graph and the x-axis if you know the initial velocity of the object

  • If the acceleration-time graph is positive this does not guarantee that the velocity will be positive