Motion Graphs (Cambridge (CIE) AS Physics): Revision Note

Motion graphs

• There are five types of graph that can represent motion 

Distance-time graphs

• On a distance-time graph…

  • slope equals speed

  • the y-intercept equals the initial position

  • a straight (diagonal) line represents a constant speed

  • a curved line represents an acceleration

  • the slope is always zero or positive because distance is a scalar quantity

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

  • the area under the curve is meaningless

Displacement-time graphs

• On a displacement-time graph…

  • slope equals velocity

  • the y-intercept equals the initial position

  • a straight (diagonal) line represents a constant velocity

  • a curved line represents an acceleration

  • a positive slope represents motion in the positive direction

  • a negative slope represents motion in the negative direction

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

  • the area under the curve is meaningless

Displacement-time graphs for different scenarios

The displacement-time graph for constant velocity is a straight diagonal line, and for acceleration is a curve

Speed-time graphs

• On a speed-time graph…

  • slope equals acceleration

  • the y-intercept equals the initial speed

  • a straight line represents uniform acceleration

  • a curved line represents non-uniform acceleration

  • a positive slope represents an increase in speed 

  • a negative slope represents a decrease in speed 

  • a zero slope (horizontal line) represents motion with constant speed

  • the area under the curve equals the distance travelled

Velocity-time graphs

• On a velocity-time graph…

  • slope equals acceleration

  • the y-intercept equals the initial velocity

  • a straight line represents uniform acceleration

  • a curved line represents non-uniform acceleration

  • a positive slope represents an increase in velocity in the positive direction

  • a negative slope represents an increase in velocity in the negative direction

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

  • the area under the curve equals the displacement 

Velocity-time graphs for different scenarios

The velocity-time graph for constant velocity is a straight horizontal line, for acceleration is a straight diagonal line and for increasing acceleration is a curve

Acceleration-time graphs

• On an acceleration-time graph…

  • slope is meaningless

  • the y-intercept equals the initial acceleration

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

  • the area under the curve equals the change in velocity

Acceleration-time graph for different scenarios

The acceleration-time graph for constant velocity is blank, for increasing velocity is a straight horizontal line and for increasing acceleration is a straight diagonal line