Friction is something you experience every day from drawing on paper, going down a slide, or even just walking around. Explore this activity to learn more about this common force in physics!
1. Pour some rice in the bottle.
2. Stick your pencil into the rice in the bottle.
3. Try to pull your pencil back out.
4. Repeat steps 1 – 3 until your pencil does not come out easily. Can you lift the bottle by just pulling the pencil up?
What’s happening? Friction happens anytime an object resists moving when another object rubs or pushes against it. If you have a big block on the ground, it is hard to push forward because of the friction between the box and the ground.
When you put the rice into the bottle, there are air gaps between each grain. Each time you push the pencil in, the rice in the bottle packs down and the air gaps become smaller. This creates more friction between the rice grains and between the rice and the pencil. Eventually, the friction becomes so strong between the rice and the pencil that you are able to pick up the bottle.