Phone Book Friction Physics

What happens when you interleave the pages of two books or pads of paper? Why?

The friction between two objects determines how difficult it will be to slide one object across another. Friction accounts for how your feet move across grass, for example, compared to how an ice skate moves across ice. Scientists use both the coefficient of friction and measurement of normal force to talk about how much friction exists between objects.

In this week's family science activity, families explore properties related to friction by experimenting with phone books (or even pads of paper). Phone books are traditionally large but have very thin paper. When a few pages are interleaved, you may find the books pull apart easily. But the results change as you interleave more and more pages. What observations can you make about friction in this process? How many pages have to be interleaved before the books resist being pulled apart? Does it matter what size books you use?

Put friction to the test with this fun family physics activity:

• Phone Book Friction (science activity at Science Buddies)
• Phone Book Friction (science activity at Scientific American)

Making Connections

For other hands-on science projects related to this exploration of friction, see the following:

• Try the Mythbusters' "Phone Book Friction" Experiment at Home
• Sliding and Friction