Motion Graphs (OCR A Level Physics): Revision Note

Motion Graphs

• Three types of graph that can represent motion are displacement-time graphs, velocity-time graphs and acceleration-time graphs

Displacement-Time Graph

• On a displacement-time graph:

  • The gradient (or slope) equals velocity

  • The y-intercept equals the initial displacement

  • A diagonal straight line represents a constant velocity

    • A positive slope represents motion in the positive direction

    • A negative slope represents motion in the negative direction

  • A curved line represents an acceleration

  • A horizontal line (zero slope) represents a state of rest

  • The area under the curve is meaningless

• Remember the displacement-time graph can have positive or negative values on the displacement axis. However, a distance-time graph only has positive

Displacement-time graph for different scenarios

Velocity-Time Graph

• On a velocity-time graph:

  • Slope equals acceleration

  • The y-intercept equals the initial velocity

  • A straight line represents uniform acceleration

    • A positive slope represents an increase in velocity (acceleration) in the positive direction

    • A negative slope represents an increase in velocity (acceleration) in the negative direction

  • A curved line represents the non-uniform acceleration

  • A horizontal line (zero slope) represents motion with constant velocity

  • The area under the curve equals the displacement or distance travelled

• Remember the velocity-time graph can have positive or negative values on the displacement axis. However, a speed-time graph only has positive

Velocity-time graph for different scenarios

Acceleration-Time Graph

• On an acceleration-time graph:

  • The slope is meaningless

  • The y-intercept equals the initial acceleration

  • A horizontal line (zero slope) represents an object undergoing constant acceleration

  • The area under the curve equals the change in velocity

Acceleration-time graphs for different velocity scenarios