Goal of the experiment: Learning about friction, that is the force that opposes the movement of one substance against another.
Materials: - Enough rice to fill a medium sized plastic bottle
- Pencil or chopstick
- Funnel to get rice into the bottle
- Medium sized plastic or glass bottle
- A scoop to get rice to the funnel
Steps of the experiment:
- Bring out the materials and ask the child: “Do you think I can lift a bottle of rice with a chopstick?”
- Pour rice into a bowl for easy access
- Place funnel into bottle
- Scoop rice and pour into funnel (that is already in the opening of the bottle)
- Bang the bottle gently on the table to settle the rice (key point)
- Continue until mostly full
- Place the chop stick into the bottle
- Work it into the rice, gently banging the bottle to get the chop stick worked well into the rice
- Once worked into the rice, grab the chopstick and try to lift the bottle
- Observe the wonder
As the rice sits in the bottle, there are air pockets around most grains, which prevents friction. As we push the chop stick into the bottle, the grains of rice settle close to one another eliminating most of the air pockets. Once this happens, the frictional force overwhelms the rice and so the rice will push against the chop stick. In fact, the grains are pushing so forcefully, they create a force that causes the chopstick to become stuck enabling you to pick up the bottle of rice.