Since both objects have mass, they both have a force of gravity acting on them. By Newton's Law of Universal Gravitation, we know that the force of gravity acting on the book will be greater than the force of gravity acting on the paper. If the book has 30 pages and no cover, it will have a force of gravity 30 times greater than a single page from that book (this is the approximate scale used in the diagram at left).

Both objects also have some air resistance acting on them. The size of the air resistance force depends on two things: speed and cross sectional area. The cross sectional area is the same for each object. The book is traveling more quickly than the paper, so it must have a bigger air resistance force acting on it.

The air resistance force acting on the paper is certainly significant, because if we crumple the paper, it will have less air resistance and fall with the same motion as the book. However, the air resistance on the book is probably not significant. Try dropping 2 identical books, one held horizontally (as in the above scenario) and one held vertically. The vertical book has less cross-sectional area and should have less air resistance. Both books hit the ground at the same time, indicating that the air resistance is too small to have a noticeable effect for either book. Thus, we say the air resistance on the book is insignificant, even though there is more air resistance on the book than on the paper! We judge significance by comparing the size of the force relative to other forces acting on that object.