Now try and pull the books apart.

Which of the following is correct?

1.It is easy to pull the books apart because the pages easily slide past one another.

2.It is difficult to pull the books apart because the pages are glued together.     

3.It is difficult to pull the books apart because friction makes the pages stick together. 

Students from all grades are invited to scan the QR code on Page 2 for the Quiz Contest.  

How does it work? 

　When two things are moving against each other, there is a ‘stickiness’ between them and that stickiness tries to slow them down or even stop them from moving completely. That ‘stickiness’ is called friction. In one experiment with two very big books, even two trucks could not pull them apart!