2C60.20-Density balls in beans

2c6020density_balls_in_beans 2c6020density_balls_in_beans_2

Video: Watch this demo

Instructor’s video

Description: This demonstration illustrates the fluid properties of granular systems.


  • 2000mL Pyrex beaker
  • Plastic beads
  • Ping pong ball
  • Metal ball similar in size to ping pong ball

Setup Procedure:

  1. Fill the beaker with the plastic beads.
  2. Bury the ping pong ball in the bottom of the beaker so that it’s not visible.

Demonstration Procedure:

  1. Put the ball bearing on top of the beads (see before picture).
  2. Shake the beaker around to “simulate” a fluid. Note: some up and down motion is necessary.
  3. After a little shaking, the ping pong ball will rise to the top of the beads and the ball bearing will sink into the beads.
  4. Explain that granular systems can act like fluids. In this case, when the beads shake, they are acting like a liquid: the denser ball will sink, and the less dense ball will rise to the top.


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