NEXT: Alice Springs

Rice Vice

You may have heard of pulling a sword from a stone, but how about a spoon from rice?

Australian Curriculum links

  • Science > Physical Sciences > Year 4 > ACSSU076

You’ll need

  • Clear empty jar or bottle, preferably plastic
  • Basmati rice
  • Wooden spoon or wooden chopstick

Try this

  1. Fill the jar with rice.
  2. Push the spoon or chopstick into the rice and wiggle it around, then remove it. Re-insert it and wiggle it around again, before removing it again. You should see the level of the rice beginning to fall.
  3. Add some extra rice, then keep inserting, wiggling, pulling-out and re-inserting the knife for several minutes. Add extra rice whenever space appears in the top of the jar.
  4. After a few minutes, you should notice that it becomes more and more difficult to insert the spoon or chopstick. Eventually, you should be able to lift up the jar just by pulling up on the embedded spoon or chopstick.

What’s happening?

When the jar is first filled with rice, the rice grains will be arranged facing in many different directions, with lots of small holes filled with air in between. By wiggling the spoon or chopstick around, you force the rice grains to line up with each other, and reduce the amount of air space (sometimes called pore space) between the rice.

As the rice grains are packed together more tightly, they push on the spoon or chopstick. Friction is a force that is experienced when two objects rub up against each other. The more the rice touches the spoon or chopstick directly (rather than air touching the object), the more friction is experienced between the spoon or chopstick and the rice. This allows you to lift the rice up using just the spoon or chopstick.

Real world links

The process of rice grains settling and organising themselves more neatly over time is similar to the process that causes pot-holes in roads. Over time, vibrations from cars can cause road-bases to compact and sink, creating potholes.