Your favorite books may contain gut-wrenching narratives, but they shouldn't be hard to wrench apart. Using all your might, can you and a friend pull them free?
Choose two similar-size books (paperback or hardcover) that have roughly the same number of pages. Place them on a table with the bottom covers overlapping by several inches (as shown), then slowly shuffle their pages together as you would playing cards.
Have a friend hold one book while you hold the other. Try to tug them apart. It's tougher than it looks!
In a good book, all the details contribute to the final result; similarly, this trick demonstrates how physical forces can accumulate. Every page that touches another produces a little bit of resistance, or friction. When you shuffle a lot of pages together, this friction adds up -- to the point that you can't pull the books apart. In other words, it makes for two very gripping reads!