A book is on top of a table. Earth's gravity exerts a constant force of 15N on the book. Why does the book not move as a result of this force?

Question

A book is on top of a table. Earth's gravity exerts a constant force of 15N  on the book. Why does the book not move as a result of this force?

drwls · Answer

The table exerts an equal upward force or 15 N on the book. The net force is zero.

Emiliy · Answer

the force of gravity is balanced by the force of friction