Why does this work?
The more contact between two surfaces, the great the friction. When you push the pencil in and out of the rice you are slowly compacting the rice and pushing air out of the container. This means that more and more rice gets in contact with your pencil which slowly but surely increases the friction between the rice and the pencil. Eventually there is so much friction you can lift the rice-filled jar or bottle into the air as the frictional forces are greater than the force of gravity.
Other friction experiment: Skewer through a balloon
Join our newsletter for more science teaching thoughts & ideas
Back to Force & Movement experiments