Why is more force needed to slide a large book across a table than to slide a small book across the table?

More force is needed to slide a large book across a table than to slide a small book primarily due to the difference in weight and surface area. A larger book typically has a greater mass, resulting in a higher gravitational force acting on it, which increases the friction between the book and the table. Additionally, the larger contact area can contribute to increased friction, requiring more force to overcome it and initiate movement.