Phone book friction : Fizzics Education

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Phone book friction

Phone book friction

Follow FizzicsEd 150 Science Experiments:

You will need:

  • Two softcover books of the same size. The more pages the better! We use old phone books as we’re less concerned if the pages get damaged, plus the soft covers make it easier to get the books together.
  • Two people to demonstrate

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Two telephone books on top of each other on a table
1 Two telephone books with their back covers opened and layered on top of each other

Open the covers of each of the books and lie one cover on top of the other as shown.

2 Pages of two telephone books layered on top of each other

Begin to layer alternate pages of each book on top of each other. The aim is to get as much contact between the book pages as possible – take your time and do as many pages as you can in the time you have!

3

Keep going until both books are weaved together. You may need to push the two book spines towards each other to keep the books together.

4 Two children holding the spines of two books that are joined together

Get your two volunteers to hold the book spines or at least the corners of the books.

5 Two kid trying to pull two books apart that are connected together

Moment of truth! Hold the spines as tight as possible and try to pull the books apart. If you have set the books up correctly you’ll find that this is very difficult!

What is going on?

This demonstration is all about friction! Friction occurs when two surfaces touch each other. The more contact between two surfaces, the more friction. Friction as opposes movement. This means the higher the friction between two surfaces, the harder it is for those surfaces to slide along each other.

By weaving as many books pages as possible together, the two books had a lot of surface area of pages touching each other and so there was a lot of friction between the book pages. Because there was a lot of friction between the books, you need to apply a lot of force to separate the books!

You would have found that the books were much easier to separate wiggle the pages to move the pages apart. Often in the classroom the only reason that the books separate is that the volunteers pull the books side to side & up and down as well as backwards. This wiggling reduces the contact between the book pages and you’re able to separate them. Under controlled conditions, it is much harder to separate the books than you might expect.

The Mythbusters tested this with two tanks and measured the forces involved!

In Todd Sampson’s Life on the Line, he took this to another level by bungee jumping with phone books connected (not an experiment to replicate!).

Variables to test

More on variables here

  • Try different size books.
  • Does glossy paper vs standard paper make a difference?

Learn more!

Learn more about friction & movement with workshops, shows & science resources.

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