Things you need:

Inseparable books

• Two paperback books which are about the same size and thickness.

Raising rice

• A non-breakable bottle or jar
• A sharpened pencil (it should be at or near full-size)
• Rice
• A funnel

The Experiment:

Inseparable books

Interleave the two books together about 4-5 pages at a time, like shuffling a deck of cards. When you have fully interleaved the books push them together so there is an overlap of about 2-3cm. The hold the two books by their spines and try to pull them apart. What happens?

Raising rice

Using the funnel if necessary, fill the container with rice, leaving some space at the top. Insert the pencil into the rice, and start stabbing! After a few stabs, the rice will settle, and you'll feel the pencil getting stuck in the rice as you try to pull it out. It will take some practice and experimentation as to what type of stabs work best. (Quick stabs work well.) Pretty soon, you won't be able to pull the pencil out and you'll be lifting the whole container of rice up along with the pencil!

So that's how it works…

Inseparable books

All that is holding the two books together is friction. When you interleave the two books there is a small force pulling the two books closed, created by the spine of the book that slightly compresses the interleaved pages. This compressive force will create a frictional force between every place the pages are interleaved, if there are 50 interleavings a small frictional force will be multiplied by 50 to create a huge force that you can't overcome with all your muscles!

Raising rice

When you pour rice into the jar the rice grains will be disorganized, meaning that there is a lot of space for the rice to move around and let the pencil move in and out freely. As you keep stabbing at the rice, they begin to organize themselves and become more compact. Soon, there will be many grains of rice pushing against the pencil with no where to move to let the pencil slide out. The friction force of each grain against the pencil is enough to lift the entire container of rice.

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