Materials

• 2 telephone books
• 2 workbooks

Procedure

• Take two telephone books and carefully place half of one inside the other. Try to pull them apart.
• Now interleave 10 pages from the books, making sure that the pages overlap with each other as much as possible. Can you pull them apart now ?
• Now interleave as many pages as you can, making sure that they are well overlapped. try to pull them apart.
• What happened ?

Observations

Rub your hands together quickly for one minute. What happened ?

Did your hands get hot when you rubbed them together ?

Did you find it got harder to pull the books apart as you interleaved more pages together?

This is called friction. Friction occurs in every situation on Earth where surfaces meet.

The greater the friction the harder you have to work to overcome it.