why does a book fall faster than paper

The force of gravity is greater on a larger mass. A book has more mass than a piece of paper, so it falls faster.
Air resistance also affects how quickly an object falls. A book has more surface area than a piece of paper, so it experiences more air resistance as it falls. This slows the book down slightly.
A third factor that affects how quickly something falls is its shape. A sphere (like a ball) falls faster than a cube (like a block). This is because the air can flow around a sphere more easily than it can around a cube, which creates more drag and slows the object down.
The combined effects of gravity, air resistance, and shape explain why a book falls faster than paper