Gripping Rice Experiment
Can you pick up a bottle of rice without touching the bottle?
What you need:
- 250mL clear, plastic bottle (or any container with a narrow neck)
- Uncooked rice
- A long, thin wooden skewer, chopstick or pencil
What to do:
- Add uncooked rice to your bottle
- Tap the bottle against a hard surface to settle the rice.
- Push the wooden skewer into the bottle until it reaches the bottom, pull it in and out several times until you’re able to lift it up!
- If the pencil is not ‘gripping’ after about thirty to forty stabs, top up the rice.
Why is it so?
Friction between the rice and skewer allows you to pick up the bottle of rice without directly touching the plastic bottle- pretty cool! This occurs because as you insert the skewer it takes up additional space in the bottle. The rice does not act like a fluid and therefore doesn’t move up the neck of the bottle as you would assume any other fluid to do. There’s not much room for the rice to move as it’s already quite packed but it tends to move downward and outward and press up against the walls of the bottle. It’s able to move a tiny distance due to the small air pockets surrounding itself. As the rice is packed more tightly the friction between each piece of rice and its nearest neighbours increases.
With the help of friction and ultimately wedging the skewer in between the rice and side of the bottle you are able to perform this floating rice bottle trick!
Extend this fun and freaky friction activity by using a different material. Why not fill the bottle with jelly beans, coffee beans or salt? Do you predict you will be able to pick it up or not? Happy experimenting!