Question 3
Gravity acts downward on a book placed on a table, yet the book does not fall to the floor. Why?
The right answer is the one marked above.
Because the table pushes the book upward. That force is called the normal reaction, and it is equal to the weight of the book.
The weight of the book bends the table top by a very small amount, and its effort to straighten pushes the book up. It is not sticking — the book lifts off perfectly easily.