4.1.9

Bouncing Ball Example

Test yourself

Motion of a Bouncing Ball

To illustrate the concepts of motion in a straight line, let's consider a ball bouncing up and down. The ball starts at rest at 10 metres.

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Displacement-time graph

  • The ball starts (at time t = 0) at a height of 10 metres.
  • The ball falls towards the ground.
  • After the ball has hit the ground, it bounces back up.
  • The same process repeats with the ball starting from a little lower each time.
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Velocity-time graph

  • To begin with (at t = 0), the ball is at rest (v = 0).
  • The ball is then released and falls towards the ground.
    • By convention, upwards is usually positive, so falling towards the ground means a negative velocity.
  • The longer the ball falls, the quicker it gets.
  • The ball hits the ground and instantaneously its velocity is reversed, it is now travelling upwards.
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Velocity-time graph 2

  • The further the ball travels upwards, the slower it gets - its velocity decreases but stays positive.
  • When the velocity decreases to zero, the ball is at the top of its bounce, instantaneously at rest.
  • The ball then falls and its velocity becomes increasingly negative.
  • The cycle is repeated for every bounce.
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Acceleration-time graph

  • The acceleration of the ball is always the same: the acceleration due to gravity.
  • The acceleration due to gravity is -9.81 m/s2.
  • It is negative because it is pulling the ball downwards.

Jump to other topics

1Measurements & Errors

2Particles & Radiation

3Waves

4Mechanics & Materials

5Electricity

6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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